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Biomedical subjects

K Fan

Publications and source records attributed to K Fan.

At least 55 records · Page 3Linked to original sources
PubMed1996

[A clinical and pathological analysis of 20 cases of lymphal follicular rectitis].

Lymphal follicular rectitis (LFR) recognized in recent years is a kind of benign lesion localizing in rectum. The lack of specific clinical and endoscopic manifestation causes the difficulty in its diagnosis. It was easily confused with ulcerative rectitis, even there were some cases which were misdiagnosed malignant rectal lymphoma. A retrograde analysis was made in our study in the 176 cases of pathologically diagnosed chronic rectitis between January 1993 and July 1994 in our hospital. Among the 176 cases, 20 were certain to be LFR (2 formerly diagnosed, 18 confirmed in the retrograde study). Endoscopic manifestations are as following: (1) granuliform proliferation, eminence and roughness can be seen in rectal mucosa with hyperemia, edema and vague vessels. The lesion is either diffused or localized. (2) single or multiple smooth polypoid apperances can be observed in rectal mucosa, which are 0.2-0.4 cm in diameter, and its pathological characteristics under microscope are: obvious lymphal follicular hyperplasia in the mucosa. A protecting zone and clear reactive germinal center in the hyperplastic follicules, coalescence of follicules occupying more than half of the lamina propria, a large amount of lymphocytes, some are in karyokinesis phase, some infiltrate the mucosa musculis and vessels proliferation in the hyperplastic lymphal tissue, scattered plasma cells, no neutrophil, no eosinophil and no abscess, which is quite different from ulcerative rectitis. Clinical manifestations of the group include: 7 intermittent hematochezia, 4 abdominal pain associated with alternative constipation and diarrhea, 2 mucous stool, 1 tenesmus, 1 pyohemofecia, 2 abdominal distension and 6 asymptomatic. From our study, the diagnosis of LFR mainly depends on its endoscopic polymorphic characteristics and specific histopathologic appearences. And it is important to differentiated LFR from other rectal diseases with lymphal tissue proliferation.

Adolescent↗
PubMed1995

Laboratory and clinical evaluation of Mycobacterium xenopi isolates.

Mycobacterium xenopi and Mycobacterium avium complex (MAC) are biochemically similar. To define the laboratory characteristics of M. xenopi that distinguish it from MAC, 53 M. xenopi isolates from different areas in the United States and 47 isolates recovered at one hospital were evaluated by 13 biochemical tests, AccuProbe MAC (Gen-Probe, Inc., San Diego, CA, USA), colony morphology, formation of X-colonies, pigmentation in response to light, growth on MacConkey agar without crystal violet, and relative growth rates at 25 degrees C, 36 degrees C, and 45 degrees C on solid media. Relative growth rates of 10 M. xenopi and 11 MAC isolates were measured at 25 degrees C, 36 degrees C, and 42 degrees C in Middlebrook broth processed using the BACTEC TB System. Ten M. xenopi were tested for p-nitro-alpha-acetylamino-beta-hydroxypropiophenone inhibition at 36 degrees C and 42 degrees C. Reevaluation of 81 isolates previously identified as MAC by biochemical tests alone revealed that two were M. xenopi. The most reliable characteristics distinguishing M. xenopi from MAC were the presence of X-colonies (M. xenopi 97% vs MAC 1%), positive 3-day arylsulfatase (M. xenopi 88% vs MAC 1%), growth at 25 degrees C (M. xenopi 0% vs MAC 100%), and AccuProbe MAC test results (M. xenopi 0% hybridized). Retrospective chart review of 37 patients using American Thoracic Society criteria revealed that six (16%) patients had clinically important isolates. At one of our hospitals M. xenopi was the second most common mycobacterial species isolated for 1990-1992, accounting for 27% of all isolates, whereas at our other hospital it accounted for 1% of isolates.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS-Related Opportunistic Infections↗
PubMed1995

[Prior enrichment of HIV-DNA with probe-DNA particles for an efficient PCR diagnosis].

PCR mediated detection of HIV-DNA has been widely used. However, compared with traditional immunological diagnoses, the extraction of DNA is a laborious and time consuming step. We have developed a procedure for the efficient isolation and concentration of HIV-DNA from cell lysates. We report here a novel method by one can recover HIV-DNA in a small volume (approximately 50 microliters) of solution from a large volume of crude cell lysate which contains as few as several copies. The method uses the specific hybridization of HIV-DNA to HIV probe-DNA particles. This prior enrichment augmented the sensitivity in the detection of HIV-DNA by PCR, and allows us to make a diagnosis even if the specimen contained an extremely low copy number of HIV-DNA molecules in a large volume, which would have otherwise resulted in false-negative data with the conventional extraction method. The method also enables the examination of 100 individual blood specimens in a combined form. Thus, the application of the present enrichment procedure with HIV probe-DNA particles should reduce the labor and cost of HIV diagnosis, since the HIV positive samples represent a very minor group of people among specimens subjected to clinical laboratory tests, and particularly, among blood samples voluntarily donated to be used for transfusions.

Base Sequence↗
PubMed1995

Prior enrichment of human immunodeficiency virus DNA with probe DNA particles for efficient PCR diagnosis.

We report here a novel method by which one can recover human immunodeficiency virus (HIV) DNA in a small volume (approximately 50 microliters) of solution from 8 ml of crude cell lysate which contains as few as several HIV DNA copies. The method uses the specific binding of HIV DNA to HIV probe DNA particles. The HIV DNA thus concentrated on the particles can be subjected to the PCR assay. The method also enables the examination of 100 individual blood specimens in a combined form.

Base Sequence↗
PubMed1994

Application of the RLGS method to large-size genomes using a restriction trapper.

We developed a method for producing restriction landmark genomic scanning (RLGS) profiles of large-size genomes, such as those of higher plants or amphibians using a restriction trapper. Use of the conventional RLGS method is limited to genomes smaller than 3 x 10(9) bp, because the larger genomic DNAs, especially those of more than 1 x 10(10) bp, produce high background due to incorporation of radioactivity at non-specifically damaged sites. Our new method reduces the background levels by reducing genome complexity to 1/200-1/300 using a purification step to enrich DNA fragments carrying specific restriction landmarks at their ends using a restriction trapper. This step makes it possible to obtain RLGS patterns of larger genomes. Our paper describes the practical application for the RLGS method using a restriction trapper with the pine tree genome (3 x 10(10) bp/haploid genome; Pinus koraiensis Sieb. et Zucc.) as an example.

DNA, Plant↗
PubMed1994

Loss of heterozygosity and overexpression of p53 gene in human primary prostatic adenocarcinoma.

We have examined the loss of heterozygosity (LOH) of codon 72 and evaluated the overexpression of the tumor suppressor gene p53 in 43 primary human prostatic adenocarcinomas (PC). DNA from tumors and normal tissues were extracted from radical prostatectomy specimens. LOH was determined by restriction fragment length polymorphism analysis (RFLP) of the codon-specific endonuclease-digested polymerase chain reaction (PCR) products. Results showed 17 heterozygous cases (39%) among this patient group. Seven of the heterozygous cases displayed LOH. Six of the seven LOH cases were high-grade PCs with Gleason's combined score of > or = 7 and showed capsular invasion. One of the LOH cases, however, displayed an intermediate morphological score of 6 but also with evidence of capsular invasion. The 43 primary PCs were also examined for overexpression of p53 by a monoclonal antibody-mediated immunofluorescence reaction. Overexpression of nuclear p53 as detected by antibody was demonstrable only in tumors with combined morphological Grade > or = 7. No significant overexpression of p53 was noted in lower-grade tumors. In addition, 10 cases of benign prostatic hyperplasia (BPH) were evaluated for p53 expression. All 10 cases showed no detectable p53 overexpression.

Adenocarcinoma↗
PubMed1993

Deregulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptor in murine macrophage cell line J774A.1.

J774A.1 immortalized macrophage tumor cells display several phenotypes and functional capacities similar to that of murine peritoneal exudate macrophages (PEM). Both populations display comparable number of M-CSF receptors. Yet the number of GM-CSF receptors on J774A.1 cells is only one-fourth that of PEM (1,500 vs. 6,000 per cell). Unlike J774A.1 cells, which constitutively express c-myc transcripts, normal PEM required rMuGM-CSF for the induction of c-myc expression. Nevertheless, the growth of J774A.1 cells can be further enhanced in the presence of exogenous rMuGM-CSF, rHuM-CSF, and rMuIL-3. Treatment with either rMuIL-3 (20 ng/ml) and rHuTGF-beta 1 (1.0 ng/ml) for 24 hr at 37 degrees C, markedly enhanced the expression of GM-CSF receptors on normal PEM but not leukemic J774A.1 cells. J774A.1 cells also did not respond by autologous upregulation of GM-CSF receptors as seen in PEM following treatment with rMuGM-CSF. Treatment with either pertussis toxin (20-100 ng/ml) or H-8 (50 microM) for 24 hr led to an enhanced expression of GM-CSF receptors on J774A.1 cells in a time- and dose-dependent manner but did not result in enhanced receptor expression on normal PEM. These findings suggest that the expression of GM-CSF receptors may be regulated by mechanisms involving Gi-proteins and their downstream elements, which in turn are linked to regulatory pathways of other cytokine receptors. In J774A.1 cells, such regulatory interaction may not exist.

Animals↗
PubMed1993

Application of rejection criteria for stool cultures for bacterial enteric pathogens.

Over 20 months, we prospectively assessed the yield of cultures for Salmonella, Shigella, and Campylobacter spp. from adults and children. In the first 10 months, 53% (567 of 1,097) of specimens from adults were from patients who had been in the hospital for > 3 days. Overall, only 2.6% (29 of 1,097) of specimens contained pathogens, and all were from patients who had been in the hospital for < or = 3 days. Over the second 10 months, specimens from adults in the hospital for > 3 days were not cultured unless special reasons existed. Thirty percent (368 of 1,229) of specimens were rejected. Concurrently, 7.5% (51 of 677) of stool specimens from children were positive. Only one positive specimen came from a child who had been in the hospital for > 3 days. Neither stool consistency nor fecal leukocytes were useful predictors for the presence of an enteric pathogen. We recommend that specimens from both adults and children in the hospital for > 3 days not be cultured unless there are delineated plausible clinical or epidemiological reasons to do so.

Adult↗
PubMed1993

Effects of sennosides and nonanthranoid laxatives on cytochemistry of epithelial cells in rat colon.

The cytochemical effects of laxatives on rat colonic epithelial cells were studied. A total of 32 rats was divided into four groups. Three groups were treated with bisacodyl, picosulfate and sennosides for 12 weeks, and a fourth group served as control. The rectum, midcolon and cecum were studied for acidic mucins, lectin soybean agglutinin (SBA) and cytokeratin AE1. Most striking and consistent changes were found in the rectum including total acidic mucin content which significantly increased, with sulfomucin decreased and sialomucin increased in the three treatment groups. Cytokeratin AE1 expression increased on picosulfate and sennosides. SBA total binding increased on bisacodyl and picosulfate. The present findings were thought to be of functional origin and do not represent early precancerous lesions.

Animals↗
PubMed1992

Up-regulation of granulocyte-macrophage colony-stimulating factor (GM-CSF) receptors in murine peritoneal exudate macrophages by both GM-CSF and IL-3.

Murine peritoneal exudate macrophages (PEM) display multiple CSF receptors. In this study, the expression of granulocyte-macrophage (GM)-CSF receptors in PEM was studied. PEM displayed over 5000 single type, high affinity GM-CSF receptors/cell with a Kd = 38 to 42 pM and an apparent molecular mass of 86,000 Da. Treatment of PEM with low, but not high, concentrations of recombinant murine (rMu) GM-CSF continuously for 24 h resulted in a marked up-regulation of GM-CSF receptors in PEM. A similar up-regulation of GM-CSF receptors also was detected in PEM cultures treated with rMuIL-3 (1-100 ng/ml) for 24 h or longer, regardless the doses of rMuIL-3 added in this case. Scatchard analysis of equilibrium binding showed that the enhanced binding activities in both cases were due to an increase in total number of GM-CSF receptors rather than changes in receptor affinity. Contrariwise, treatment with recombinant human macrophage-CSF (greater than 100-1000 ng/ml) partially inhibited the expression of GM-CSF receptors in PEM. Removal of rMuGM-CSF from culture medium 24 h after treatment led to a further up-regulation of GM-CSF receptors over a 4 to 24-h period, depending on the doses of initial treatment. On the other hand, removal of rMuIL-3 from culture medium after prolonged treatment did not result in further increase in GM-CSF receptors. The protein synthesis inhibitor cycloheximide abrogated GM-CSF receptor up-regulation induced by both rMuIL-3 and rMuGM-CSF, whereas actinomycin D inhibited only the second (8-24 h) phase of GM-CSF receptor up-regulation induced by exposure to high concentrations rMuGM-CSF (10 ng/ml). These findings suggest that rMuGM-CSF and rMuIL-3 up-regulate GM-CSF receptors in PEM in part through similar or identical metabolic pathways and provide further evidence of a close linkage between IL-3 and GM-CSF receptors.

Animals↗
PubMed1992

Transforming growth factor-beta 1 bifunctionally regulates murine macrophage proliferation.

Transforming growth factor-beta (TGF-beta) is a family of polypeptide growth factors with multiple functional activities. Recent studies suggest that TGF-beta is a selective inhibitor of hematopoietic cells. In this report, we study the effect of TGF-beta 1 on the proliferation of murine peritoneal exudate macrophages (PEM) in response to purified murine recombinant granulocyte-macrophage colony-stimulating factor (rMuGM-CSF) and human recombinant M-CSF (rHuM-CSF). In mice, PEM and other types of tissue macrophages display multiple types of receptors for CSFs and respond to them, either alone or in combination, to undergo extensive proliferation in vitro. Recombinant human TGF-beta 1 (rHuTGF-beta 1) (0.1 to 1.0 ng/mL) markedly enhanced the growth of PEM in response to rMuGM-CSF but inhibited their responsiveness to rHuM-CSF. Similar effects of rHuTGF-beta 1 were also detected using murine pulmonary alveolar macrophages (PAM) and bone marrow-derived macrophages (BMDM). Receptor binding assays using iodinated rMuGM-CSF and rHuM-CSF showed that rHuTGF-beta 1 treatment greatly enhanced the expression of GM-CSF receptors in PEM, in a time- and dose-dependent manner, suggesting a possible mechanism for the synergistic effect of TGF-beta 1. On the other hand, the expression of M-CSF receptors was not affected by TGF-beta 1 treatment. Analysis by mRNA PCR showed that the synergistic effect of TGF-beta 1 is not due to autocrine CSFs produced by treated cells. Our results suggest that TGF-beta 1 is an important regulator of macrophage proliferation. Depending on the types of CSFs present, TGF-beta 1 may act either as a growth promoter or inhibitor.

Animals↗
PubMed1992

Murine recombinant IL-4 is a bifunctional regulator of macrophage growth induced by colony-stimulating factors.

Murine peritoneal exudate macrophage (PEM) coexpress receptors for both granulocyte-macrophage CSF (GM-CSF) and macrophage CSF (M-CSF) and can be induced by both factors, either alone or in combination, to undergo extensive proliferation in vitro. In this study the effect of murine rIL-4 (MurIL-4) on the proliferation of PEM was examined. MurIL-4 alone did not support macrophage proliferation but prolonged their survival in vitro. When MurIL-4 was combined with human (Hu)rM-CSF, it enhanced the proliferative response of PEM to rHuM-CSF in a dose-dependent manner, reaching a maximum at approximately 10 ng/ml. Contrarily, MurIL-4 suppressed the proliferative response of PEM to MurGM-CSF. Receptor binding assays using radiolabeled ligands showed that MurIL-4 selectively enhanced the expression of M-CSF receptors; suggesting that at least part of the synergistic effect of MurIL-4 is mediated at the receptor level. Of relevance to this effect is the finding that MurIL-4 greatly promoted the responsiveness of PEM to low concentrations of HurM-CSF. Unlike M-CSF receptors, however, MurIL-4 treatment failed to modulate the levels of GM-CSF receptors in PEM. The proliferative responses of PEM to both MurGM-CSF and HurM-CSF could be inhibited by MurIFN-gamma with similar sensitivity. This inhibitory effect of MurIFN-gamma was partially neutralized by MurIL-4 in cultures containing HurM-CSF but not those containing MurGM-CSF. This study demonstrates that IL-4 is involved directly in the regulation of macrophage production by modulating their responsiveness to various cytokines.

Animals↗
PubMed1992

Microprocedure for in situ nick translation of chromosomes.

We have modified the procedure of in situ nick translation to shorten the autoradiographic exposure time from 1 month to 3 days and reduce the volume of nick translation solution by a factor of at least 10. The modified procedure can be carried out on individually chosen chromosome spreads. The procedure was used on chromosome spreads of three related lines of mouse mammary epithelium (+SA, -SA, CL-S1) with different degrees of tumorigenicity. We found that the autoradiographic silver grains that are observed following in situ nick translation were often placed at the apparent junction site of chromosome translocations or at the breakpoint of chromosomal pieces. We found also that silver grains were located above double minute chromosomes, which suggests that there are active genes in double minutes.

Cell Line↗
PubMed1992

Nonclonal lymphocytic proliferation in cutaneous lymphoid hyperplasia: a flow-cytometric and morphological analysis.

Cutaneous lymphoid hyperplasia, follicular B cell pseudolymphoma or lymphadenosis benigna cutis and lymphocytic infiltration of Jessner-Kanof are a group of benign lymphoid hyperplastic disorders which usually involve the skin of the face or head and neck. These lesions may be difficult to differentiate from malignant lymphocytic lymphomas both morphologically and clinically. To evaluate whether quantitative flow-cytometric analysis and DNA ploidy determination of the lymphoid cells in the lesions would provide additional and more precise diagnostic parameters, we have correlatively analyzed a case by morphological, flow-cytometric and immunohistochemical methods. The two latter methods both revealed that the lesions harbored nonclonal heterogeneous subpopulations of lymphoid cells, but 62% of the cells analyzed were of B cell lineage progenies. No pre-B cells, immature B or T determinants were detected. Ploidy analysis of the isolated lymphocytes disclosed predominantly diploid (2 N) cells with about 1% 4 N and a few (less than 5%) hyperdiploid (2.2 N) cells. Cell cycle analysis showed that 97.2% of the cells were in G0-G1 phase. Phenotyping and DNA ploidy study of the lymphocytes of the lesion may provide quantitative diagnostic parameters to distinguish this benign lesion from true lymphocytic lymphoma involvement of skin. The eventual biological behavior of the minor hyperdiploid subpopulation of lymphoid cells found in this lesion is currently uncertain, however.

Antibodies, Monoclonal↗
PubMed1988

Heterogeneous subpopulations of human prostatic adenocarcinoma cells: potential usefulness of P21 protein as a predictor for bone metastasis.

Expression of the p21 protein of the ras oncogene family was studied in a case of human prostatic adenocarcinoma tissue and the cell line was derived from the primary tumor. Flow cytometry analysis of the tumor cells obtained from the primary tumor indicated that approximately 25 per cent of the cells were positive for this oncogene product. However, by the immunoperoxidase method almost all of the tumor cells at the vertebral metastatic sites in the same patient were positive for the p21 protein. The cell line established from the primary tumor displayed 2 distinct subpopulation growth patterns in vitro: a monolayer, density-inhibited growth and a multicellular aggregate type growth morphology. These 2 subpopulations could be separated by density elutriation centrifugation. The isolated subpopulation cells were noted to express prostatic acid phosphatase and prostate specific antigen at high frequency. High levels of expression of these 2 prostatic markers also were found in the tumor cells at the vertebral metastatic sites. However, when the isolated subpopulations were analyzed for the expression of p21 protein, the multicellular grown cells were almost 90 per cent positive for the p21 antigen, whereas only approximately 5 per cent of the monolayer grown cells were positive for the same protein. Our findings suggest that primary prostatic carcinomas are composed of heterogeneous subpopulations of neoplastic cells while only specific subpopulations have metastatic potential. Quantification of prostatic acid phosphatase and prostate specific antigen in the primary tumor cells probably will not offer a predictive value for the eventual behavior of the tumors. However, evaluation of oncogene products, such as the p21 protein, may be useful as a clinical predictor for metastatic potential.

Acid Phosphatase↗
PubMed1987

Amiodarone-associated pulmonary fibrosis. Evidence of an immunologically mediated mechanism.

A case of pulmonary fibrosis attributed to amiodarone was studied immunologically and morphologically. A specific antibody of the IgG class was identified in the serum of this patient which reacted with the patient's own lung tissue. The immunoglobulin did not react with normal lung tissue nor was there evidence of reaction with lung tissue from patients with pulmonary fibrosis but without a history of amiodarone therapy. The patient probably developed a humoral antibody response to a lung-amiodarone complex with the amiodarone acting as a hapten which bound in vivo to the lung tissue. The subsequent antibody-antigen reaction stimulated a proliferation of pulmonary fibroblasts and probably enhanced the fibro-collagen deposition in the lung.

Amiodarone↗
PubMed1985

Co-culture study of rat neuron-glial interaction: evidence of neuronal influence on myelination.

Organotypic cultures of newborn rat brains were exposed to the neurotoxin kainic acid or the DNA synthesis inhibitor arabinoside C. The cultures were subsequently co-cultured and the myelination-related enzymatic activities, such as 2',3'-cyclic nucleotide phosphohydrolase and uridine diphosphate-galactose-ceramide galactosyl transferase, were determined under various culture conditions. The newly formed myelin basic protein in the cultured brain tissue was determined by the radioimmunoprecipitation method. The myelination-related enzymatic activities and the synthesis and accumulation of myelin basic protein in the co-cultured brain tissue were found compatible to the control cultures which were not exposed to either drug. The cultures which had been treated with either drug, but not subsequently co-cultured, were found to have decreased enzymatic activities and myelin basic protein synthesis. The experimental data suggest that myelinogenesis requires an interaction between functional neurons and oligodendroglial cells and further supports the hypothesis that the neuron exerts a regulatory effect on the glial myelination mechanism.

2',3'-Cyclic Nucleotide 3'-Phosphodiesterase↗