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Biomedical subjects

L X Pan

Publications and source records attributed to L X Pan.

32 records · Page 2Linked to original sources
PubMed1994

Clonality analysis of defined B-cell populations in archival tissue sections using microdissection and the polymerase chain reaction.

A simple microdissection technique involving the use of a drawn-out glass pipette was developed for isolation of defined cell subsets from tissue sections. Using this technique and the polymerase chain reaction (PCR), clonally rearranged immunoglobulin (Ig) heavy chain genes were reliably amplified in single neoplastic follicles or few hundreds of tumour cells isolated from archival haematoxylin and eosin or immunostained sections of B-cell lymphomas. A polyclonal nature was consistently demonstrated in reactive lymphoid follicles or interfollicular reactive B-cells within the same lymphoma sections. Microdissection of lymphoma cells from within foci of chronic inflammation improved the resolution of tumour-specific PCR products by reducing amplification of background polyclonal B-cell sequences. The combination of microdissection and PCR techniques, therefore, provides an important tool for the investigation of B-cell lymphomas and also allows simple and specific access for other molecular genetic analyses of different cell subsets on tissue sections.

B-Lymphocytes↗
PubMed1994

Multiple PCR analyses on trace amounts of DNA extracted from fresh and paraffin wax embedded tissues after random hexamer primer PCR amplification.

AIM: To establish a simple and reliable polymerase chain reaction (PCR) methodology for random amplification of whole genomic DNA from limited histopathological samples. METHODS: Trace amounts of genomic DNA extracted from fresh tissue and individual lymphoid follicles microdissected from archival paraffin wax tissue sections were amplified using a two-phase PCR protocol with random hexamers as primers (RP-PCR). The randomly amplified DNA samples were used as templates for specific PCR amplifications. To check the fidelity of the RP-PCR, products of the specific PCR amplifications were further analysed by single stranded conformation polymorphism (SSCP) or sequencing. RESULTS: Using a minute fraction of RP-PCR template pool, multiple PCR analyses, including those for beta globin gene, p53 gene (exon 5-6, exon 7, exon 8-9 and exon 7-9), and rearranged immunoglobulin heavy chain gene fragments (VH framework 3 to JH and VH framework 2 to JH) were successfully performed. No artefactual mutations were identified in the products of these specific PCR reactions by SSCP or sequencing when compared with the products from the original DNA. CONCLUSION: This method is simple and reliable, and permits multiple genetic analyses when only a limited amount of tissue is available.

Base Sequence↗
PubMed1993

Primary low-grade B-cell lymphoma of the conjunctiva: a mucosa-associated lymphoid tissue type lymphoma.

We describe the clinical presentation, morphology, immunophenotypic features and molecular biology of seven cases of conjunctival lymphoid infiltration. In five cases there was either immunophenotypic or molecular evidence of B-cell lymphoma. Each of these cases showed the morphological, immunophenotypic and molecular feature of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type. The findings suggest that most conjunctival lymphomas are of this type and explains their uniformly favourable prognosis.

Adult↗
PubMed1992

Cytogenetic study of B-cell lymphoma of mucosa-associated lymphoid tissue.

The recently described B-cell lymphomas arising in mucosa-associated lymphoid tissue (MALT) form a distinct clinico-pathologic group of non-Hodgkin's lymphoma, and therefore would be expected to be characterized by a recurrent chromosomal aberration. We have analyzed the cytogenetics of 23 cases of MALT lymphomas arising in the stomach, small intestine, lung, and lacrimal gland. In each case the presence of an abnormal clonal cell population was confirmed by the identification of rearranged bands when digested tumor DNA was hybridized with a probe to the joining region of the immunoglobulin heavy chain gene. Metaphase spreads were obtained in 14 cases, of which 9 cases showed an abnormal karyotype. Although no unifying aberration was detected, rearrangements of chromosome 1p, and numerical abnormalities of chromosomes 3 and 7, may play a role in the genesis of these tumors.

Chromosome Aberrations↗
PubMed1991

Cellular H- and M-type lactate dehydrogenase (LDH) isoenzymes and tumour diagnosis--an immunohistochemical assessment.

Cellular H- and M-type lactate dehydrogenase (LDH) isoenzymes were determined immunohistochemically in a wide range of normal, inflammatory, benign neoplastic, and malignant tissues to assess the possible value of the isoenzymes in tumour diagnosis. Both types of LDH were detected almost ubiquitously in normal tissues. Increased staining intensity of LDH, especially M-type LDH, was demonstrated in most types of malignant tumours studied. Similar increased staining intensity of the isoenzymes was also noted to parallel the proliferative activity of the cells in non-neoplastic diseases and benign neoplasms. The results suggest that changes of cellular H- and M-type LDH isoenzymes are not specific for any type of malignant tumours. The increase in cellular H- and M-type LDH isoenzymes appears to be related to proliferation of cells in general.

Biomarkers, Tumor↗
PubMed1991

Follicular colonization in B-cell lymphoma of mucosa-associated lymphoid tissue.

The formation of neoplastic B-cell follicles is universally accepted as diagnostic of a follicle centre cell (FCC) lymphoma. Low-grade B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) are characterized by a diffuse infiltrate of cells of uncertain lineage known as "centrocyte-like" cells because of their resemblance to centrocytes (small cleaved cells). Some MALT lymphomas, however, contain numerous follicles and may even have a predominantly follicular appearance. These follicles may be reactive or show immunoglobulin (Ig) light-chain restriction, indicating their neoplastic nature. We have proposed that these neoplastic follicles are not composed of follicle centre cells but result from colonization of reactive follicles by CCL cells. In this study, the immunophenotype and genotype of 10 primary gastrointestinal lymphomas with a follicular component have been determined. One case exhibited the morphological, immunophenotypic, and genotypic features of FCC lymphoma (Ig light-chain restriction, CD10+, KB61 (CDw32)-, Jh, and bcl-2 gene rearrangement). Neoplastic follicles in the remaining nine cases, which showed the features of MALT lymphoma, were of a different phenotype (Ig light-chain restriction, CD10- KB61(CDw32)+), and these lymphomas showed Jh but not bcl-2 gene rearrangement. Taken in conjunction with the morphological features, these findings suggest that in these cases the neoplastic follicles formed as the result of colonization of previously reactive follicles by neoplastic CCL cells. Thus, not all lymphomas containing neoplastic follicles are of FCC origin. Follicular colonization, as seen in low-grade MALT lymphomas, is likely to be a recapitulation of an as yet undescribed normal immunological phenomenon that may involve marginal zone B cells.

Gene Rearrangement↗
PubMed1990

A genotypic study of low grade B-cell lymphomas, including lymphomas of mucosa associated lymphoid tissue (MALT).

Genotypic analysis has led to the implication of certain oncogenes in the pathogenesis of specific groups of non-Hodgkin's lymphoma. Rearrangements of c-myc are associated with Burkitt's lymphoma and of bcl-2 with centroblastic/centrocytic lymphoma. Rearrangement of bcl-1 has yet to be associated with a specific group of lymphoma. In this study DNA from 62 cases of low grade B-cell lymphoma, classified using the Kiel classification, were analysed by Southern blotting and hybridization with probes to bcl-1, bcl-2, and c-myc. Rearrangements of bcl-2 were found in a proportion of centroblastic/centrocytic lymphoma comparable to other published studies. Rearrangement of c-myc was not found in any case studied. Bcl-1 rearrangement was found in 2/9 cases of B-CLL, and 3/6 cases of centrocytic lymphoma. This incidence of bcl-1 rearrangement in centrocytic lymphoma suggests that it is a characteristic change. No rearrangement of bcl-1, bcl-2 or c-myc was found in any case of lymphoma of mucosa associated lymphoid tissue (MALT), providing further evidence that, in spite of having a similar morphology to some other groups of low grade B-cell lymphoma, lymphomas of MALT comprise a distinct entity.

Blotting, Southern↗
PubMed1989

Production of monoclonal antibodies to lactate dehydrogenase (LDH) isoenzymes for immunohistochemical study on fixed tissue section.

Purified lactate dehydrogenase (LDH) isoenzyme 1 (H or B subunits) and isoenzyme 5 (M or A subunits) were used to prepare monoclonal antibodies (MAb) suitable for immunohistochemical detection on formalin fixed paraffin-embedded tissue sections. In the initial fusions, screening of the antibodies was based on enzyme linked immunosorbent assay (ELISA) against the immunogens. None of the antibodies obtained was satisfactory. There were various problems related to specificity, crossreactivity, affinity and also the properties of the monoclonal antibody itself. Using a combined system involving more than one method for screening, two suitable monoclonal antibodies, MAb65 (to H-type LDH) and MAb25 (to M-type LDH) were selected. Both antibodies reacted specifically with corresponding LDH isoenzymes as shown in a series of tests. Their reactivity in sections of formalin fixed paraffin-embedded tissue indicated that both antibodies are suitable reagents for immunohistochemical studies.

Animals↗
PubMed1987

The effect of dietary zinc and prothymosin alpha on cellular immune responses of RF/J mice.

Mice of the RF/J strain on a normal diet are defective in some aspects of cellular immunity, as evidenced by their susceptibility to infection with Candida albicans, their failure to release detectable quantities of circulating migration inhibitory factor (MIF) in vivo, and the presence of a low rate of phagocytosis and killing by peritoneal macrophages. When the mice were fed a high-zinc diet (300 ppm) for 4 weeks and then treated daily with 160 ng prothymosin alpha, an increase occurred in resistance to infection with C. albicans, in the capacity to release MIF in vivo into the circulation and in the capacity of peritoneal macrophages to engulf (phagocytose) and kill cells of C. krusei. In addition, the number of spleen lymphocytes producing antibody to a T-dependent antigen was significantly increased in the mice fed a high-zinc diet and inoculated daily with prothymosin alpha.

Animals↗
PubMed1986

Human prothymosin alpha: amino acid sequence and immunologic properties.

Prothymosin alpha has been purified from human thymus and its amino acid sequence determined, except for a 15 amino acid segment including 10 glutamyl residues near the middle of the molecule. Like prothymosin alpha from rat thymus [A. A. Haritos, R. Blacher, S. Stein, J. Caldarella, and B. L. Horecker (1985) Proc. Natl. Acad. Sci. USA 82, 343-346], human prothymosin contains the thymosin alpha 1 sequence at its NH2-terminus. It contains a total of 109-110 residues compared to 111-112 for rat prothymosin alpha, with deletions corresponding to positions Gln39 and Lys108 of the rat polypeptide. Human prothymosin alpha also differs from rat prothymosin alpha at positions corresponding to residues 87, 92, and 102 of the latter, with substitutions of alanine for proline, alanine for valine, and aspartic acid for glutamic acid, respectively. Human prothymosin is significantly less active than rat prothymosin in protecting mice against infection with Candida albicans and in stimulating release in vivo of migration inhibitory factor. Thus, the differences in amino acid sequences, present mainly the COOH-terminal half of the polypeptides, may determine species specificity in biological properties.

Amino Acid Sequence↗
PubMed1986

The primary structure of rat parathymosin.

Parathymosin has been isolated from rat thymus and from rat liver. Its primary structure is reported as follows: (Sequence; see text). The blocking group at the NH2 terminus was identified by mass spectrometry as acetyl. Regions homologous to amino acid sequences in prothymosin alpha were found to be located between residues 14-20, 23-25, 33-39, 41-43, and 83-87 of parathymosin.

Amino Acid Sequence↗
PubMed1980

The significance of 5'-nucleotide phosphodiesterase isozymes in the diagnosis of liver carcinoma.

The results of determination of the serum 5'-NPDase isozymes in 95 cases of primary liver carcinoma and other kinds of disease are presented. The 5'-NPDase-V was positive in 83.2% of primary liver cancer cases. This test might be a useful supplement to AFP determination, especially in AFP-negative liver cancer patients. In most patients who had undergone successful liver resection for primary carcinoma, the test became negative. A positive 5'NPDase-V test in patients with cancer elsewhere in the body may suggest liver metastasis. In addition, this test may be of some help in the differentiation of primary liver cancer from other kinds of liver disease. The problem of "false-positive" results of this test is discussed.

Diagnosis, Differential↗