Search PubMed⌕ Search

Biomedical subjects

L Pan

Publications and source records attributed to L Pan.

At least 145 records · Page 8Linked to original sources
PubMed1995

[A clinical and experimental study of L-form bacteria in 66 cases].

In order to study the relationship between the time for establishing the diagnosis of infectious diseases and L-form bacteria, a series of clinical specimens taken from 321 cases of patients suspected to have infection were collected. Besides routine bacterial culture, special culture for L-form bacteria was also performed. The results were as follows: the rate of positive routine bacterial culture was 10.90% (35/321); the rate of negative routine bacterial culture but positive L-form bacterial culture was 20.56% (66/321). In this study, L-form bacteria infection was treated with sensitive antibiotics and a satisfactory result was obtained. It is shown that L-form bacterial culture is very useful in detection of pathogenic bacteria and helpful to the therapy of infectious diseases. Ultrastructure organization of these bacteria was studied by using transmission electron microscope.

Adult↗
PubMed1994

Neurotrophic factor receptors and their signal transduction capabilities in rat astrocytes.

Until recently, astrocytes were not considered as sites for neurotrophic factor action. We show here that, both in vivo and in vitro, astrocytes express receptors for two separate families of neurotrophic factors. In the intact adult rat CNS, astrocytes express the extracellular domain of the neurotrophin receptor TrkB and, in a more restricted population, the low-affinity nerve growth factor receptor p75LNGFR. In the lesioned CNS, expression of the alpha component of the receptor for ciliary neurotrophic factor (CNTFR alpha) switches from a purely neuronal localization to cells in the glial scar at the edge of the wound. Using cultured hippocampal astrocytes as a model to address the functional status of these receptors, we have found only the truncated forms of TrkB and TrkC, which are incapable of signal transduction as measured by protein tyrosine phosphorylation or immediate early gene induction. In contrast, a fully functional CNTF receptor complex capable of signal transduction is present on cultured astrocytes. Thus, the neurotrophin receptors may act primarily to sequester or present the neurotrophins, whereas in the case of CNTF a functional response can be initiated within the astrocyte.

Animals↗
PubMed1994

Sources of DNA for detecting B cell monoclonality using PCR.

AIMS: To evaluate the polymerase chain reaction (PCR) demonstration of clonal immunoglobulin heavy chain gene rearrangements using routinely prepared, unstained, and stained formalin fixed, paraffin wax embedded tissue samples. METHODS: Extracts from (a) fresh frozen tissue samples, (b) unstained, and (c) haematoxylin and eosin stained formalin fixed, paraffin wax embedded 5 microns tissue sections from 42 cases of low grade B cell lymphoma, all shown to be monoclonal by Southern blot analysis, were analysed using PCR. Two regions of the variable segment of the immunoglobulin heavy chain gene were amplified (framework 2 to joining region [Fr2/JH] and framework 3 to joining region [Fr3/JH]). Twelve samples of reactive lymphoid tissue were studied as controls. Products from each case were directly compared on polyacrylamide gels. RESULTS: Using both primer combinations, monoclonality was detected in 38 of 42 (90%) cases using fresh material, 37 of 42 (88%) using unstained paraffin wax embedded samples, and in 35 of 42 (83%) cases using haematoxylin and eosin stained sections. No false positive results attributable to fixation, processing, or staining were identified, although the efficiency of amplification using the Fr2/JH primers was significantly reduced. CONCLUSIONS: PCR determination of B cell clonality using paraffin wax embedded material is sufficiently sensitive and reliable for use as a routine diagnostic adjunct to conventional morphological and immunocytochemical assessment of lymphoproliferative disease.

Base Sequence↗
PubMed1994

A case-control epidemiologic study of endometriosis.

A case-control study involving 203 cases of pelvic endometriosis seen from 1987-1989, and 406 randomly selected and age-matched community controls was conducted in order to provide information relevant to effective prophylaxis of the disease. The diagnosis was confirmed by pathology from laparotomy and/or laparoscopy. A questionnaire focused on menstrual, marital and reproductive status, professional exposure and physical activities, and the results were analyzed by a conditional logistic regression model. Women characterized by earlier menarche (< or = 12 years) and longer period (> or = 8 days) were found to be associated with an elevated incurring risk, and a trend of increasing risk associated with primary dysmenorrhea (RR = 2.1 for mild to moderate and RR = 5.2 for severe dysmenorrhea), energetic physical activity during menstruation (RR = 2.1), and allergic diathesis (RR = 1.8) was seen. An inverse relationship was observed between the number of pregnancies and risk of endometriosis, and the protective effect was most significant when only the number of full-term pregnancies was counted. The risk factors of endometriosis are discussed, and intensive treatment of primary dysmenorrhea and avoidance of strenuous exercise during menstruation are identified as important measures in the prevention of endometriosis.

Adult↗
PubMed1993

Effect of morphine on urine output: possible role of atrial natriuretic factor.

We examined the possible role of atrial natriuretic factor (ANF) in morphine-induced diuresis. Morphine (20 micrograms/20 microliters) administered intracerebroventricularly (i.c.v.) in conscious, normally hydrated Sprague-Dawley rats significantly increased urine output from 0.22 +/- 0.16 ml/h/rat to 2.07 +/- 0.46 ml/h/rat, 3 h after injection. Morphine injection also significantly increased the plasma ANF level to a maximum of 364 +/- 46 pg/ml compared to control animals (33 +/- 7 pg/ml) in which 20 microliters of saline was injected i.c.v. (P < 0.001). This peak increase occurred 1 h after morphine administration, however, it continued to remain significantly elevated (171 +/- 36 pg/ml vs. 39 +/- 8 pg/ml in control animals; P < 0.001) 2 h later. The maximal diuresis observed 3 h after administration of morphine i.c.v. was abolished by pretreatment of the animals with 0.8 mg of naloxone given intravenously (i.v.) and also by anti-rat ANF serum (0.4 ml i.v.). A short, transient increase in blood pressure, occurred 2-5 min after morphine administration, but it is unlikely that this increase accounted for the increase in plasma ANF. We conclude that the diuresis induced by i.c.v. administration of morphine is due to enhanced release of ANF.

Animals↗
PubMed1993

Regression of primary low-grade B-cell gastric lymphoma of mucosa-associated lymphoid tissue type after eradication of Helicobacter pylori.

Certain features of primary low-grade B-cell gastric lymphoma of mucosa-associated lymphoid tissue (MALT) suggest the tumour is antigen-responsive. Given the close association between gastric MALT lymphoma and Helicobacter pylori, these organisms might be evoking the immunological response, and eradication of H pylori might inhibit the tumour. 6 patients in whom biopsies showed histological and molecular-genetic evidence of low-grade gastric B-cell MALT lymphoma with H pylori infection were treated with antibiotics. In all cases H pylori was eradicated and in 5, repeated biopsies showed no evidence of lymphoma. These results suggest that eradication of H pylori causes regression of low-grade B-cell gastric MALT lymphoma, and that anti-H-pylori treatment should be given for this lymphoma.

Adult↗
PubMed1993

LIFR beta and gp130 as heterodimerizing signal transducers of the tripartite CNTF receptor.

The ciliary neurotrophic factor (CNTF) receptor complex is shown here to include the CNTF binding protein (CNTFR alpha) as well as the components of the leukemia inhibitory factor (LIF) receptor, LIFR beta (the LIF binding protein) and gp130 [the signal transducer of interleukin-6 (IL-6)]. Thus, the conversion of a bipartite LIF receptor into a tripartite CNTF receptor apparently occurs by the addition of the specificity-conferring element CNTFR alpha. Both CNTF and LIF trigger the association of initially separate receptor components, which in turn results in tyrosine phosphorylation of receptor subunits. Unlike the IL-6 receptor complex in which homodimerization of gp130 appears to be critical for signal initiation, signaling by the CNTF and LIF receptor complexes depends on the heterodimerization of gp130 with LIFR beta. Ligand-induced dimerization of signal-transducing receptor components, also seen with receptor tyrosine kinases, may provide a general mechanism for the transmission of a signal across the cell membrane.

Animals↗
PubMed1993

Characterization of two 11q23.3-11q24 deletions and mapping of associated anonymous DNA markers.

Translocations in bands 11q23.3-11q24 are associated with several human cancers, including acute lymphoid and acute myeloid leukemias (AML) and Ewing's sarcoma. We have characterized two independent deletions in this region, one derived from a patient with AML who previously had a T-cell lymphoma, and another from a Wilms' tumor patient. Cytogenetic analysis of the ML-2 cell line established from the malignant cells of the AML patient indicated that one chromosome 11 homolog had an interstitial deletion, del(11) (q23q24), and the remaining homolog was involved in a recurring translocation, t(6;11) (q27;q23). According to karyotype analysis on the Wilms' tumor patient (EH), one chromosome 11 was normal and the other carried an interstitial deletion at 11q23.3-11q25. Somatic cell hybrids segregating the EH deletion (EHR4) and the ML-2 deletion (MLR4) have been isolated. The EH deletion is distal to the MLL probe recently associated with 11q23.3 leukemia breakpoints (Ziemin-van der Poel et al.: Proc Natl Acad Sci USA 88:10735-10739, 1991). The ML-2 deletion could involve the MLL gene at a point distal to other breakpoints within MLL. Both deletions include the Ewing's sarcoma breakpoint at 11q24.1. By Southern blot analysis we identified three anonymous DNA markers (D11S272, D11S273, and D11S219) and the ETS/oncogene, which map within each deleted region. These markers are conserved based on zoo blot analysis, and they are valuable for physical mapping and genetic characterization of a region that may code for gene products associated with growth control and tumor suppression in a variety of cancers.

Animals↗
PubMed1993

Detection of monoclonality in low-grade B-cell lymphomas using the polymerase chain reaction is dependent on primer selection and lymphoma type.

Detection of B-cell monoclonality using the polymerase chain reaction (PCR) promises the quick and cost-effective separation of monoclonal from polyclonal B-cell disease. However, the efficiency of the method has yet to be fully assessed, particularly with regard to disease type and selection of PCR primers. We have evaluated two approaches based on amplification of the immunoglobulin heavy chain gene using framework 2 (Fr2) and framework 3 (Fr3) region primers. Frozen tissue samples from 94 cases of low-grade B-cell lymphoma were investigated, all of which had previously been shown to be monoclonal by Southern blot analysis. Using a Fr2 primer, we were able to show monoclonality in 85 per cent of cases; with Fr3, 80 per cent of cases; and using both techniques in separate reactions, 90 per cent of cases. Thus, a significant false-negative rate exists with either primer which can be reduced by using both. We also found a difference in the efficiency of detection in different types of lymphoma; only 87 per cent of mucosa-associated lymphomas and centroblastic/centrocytic lymphomas were shown to be monoclonal, whereas all of the other lymphoma types tested were positive using one or both methods. We conclude that PCR detection of B-cell monoclonality allows rapid analysis of tissue samples, including paraffin-processed material. False-negative results which occur in some types of lymphoma can be reduced by the use of two or more primer combinations.

Base Sequence↗
PubMed1993

Epstein-Barr virus (EBV) in enteropathy-associated T-cell lymphoma (EATL).

Using Southern hybridization analysis, we have detected the Epstein-Barr virus (EBV) genome in 36 per cent (4/11) of enteropathy-associated T-cell lymphoma (EATL), a frequency much higher than that seen in nodal T-cell lymphomas in which we were able to show EBV DNA in only 3 per cent (1/30) of the cases examined. Using a terminal fragment probe, monoclonal proliferation of EBV in infected cells was demonstrated in three of the four EBV-positive EATL cases (in one case, insufficient signal prevented the determination of EBV clonality). The EBV genome and an early transcript, EBER1, were identified in tumour cells by in situ hybridization. Expression of latent membrane protein (LMP) was detected in two EBV DNA/RNA-positive EATL cases. In view of the known oncogenic properties of EBV and the putative central role of LMP in EBV-induced cell immortalization, the results of this study suggest that the virus may play an aetiological role in the pathogenesis of EATL.

Blotting, Southern↗
PubMed1993

In situ detection of human Ig light-chain mRNA on formalin-fixed and paraffin-embedded tissue sections using digoxigenin-labelled RNA probes.

Digoxigenin-labelled RNA probes complementary to human immunoglobulin (Ig) kappa and lambda light-chain mRNAs were produced by in vitro transcription. Using these probes, several existing in situ hybridization protocols were studied. By modifying and optimizing pretreatment procedures, which include hybridization, stringency washings and probe detection, a simplified non-radioactive in situ hybridization method for Ig light-chain mRNAs was developed. The light-chain signals were consistently identified in plasma cells, germinal centrocytes, centroblasts and immunoblasts in formalin-fixed and paraffin-embedded sections of lymphoid tissues. Monotypic light-chain mRNA was demonstrated in archival cases of kappa or lambda light-chain-restricted B-cell lymphoma. Background staining was found to be negligible in all the tissues tested. These results indicate that the in situ hybridization methodology described in this study is specific and sensitive for the detection of Ig light-chain mRNAs and has practical value in routine histology.

Antisense Elements (Genetics)↗
PubMed1993

[Actinomyces-like organisms infection in intrauterine devices wearers].

The prevalence of actinomyces-like organisms in cervicovaginal smears of 2,327 Chinese women, including 1,279 intrauterine devices (IUD) wearers and 1,048 non wearers, was investigated. Cervical smears were stained by the Papanicolaou method for the microscopic examination of actinomyces-like organisms. The relationship between actinomyces-like organisms infection and occupations, age, duration of IUD wearing and clinical symptoms were analysis. The result showed that the overall detection rate of actinomyces-like organisms in 2,327 women was 0.69%. The detection rates in IUD wearers and non-wearers were 1.1% and 0.2%, respectively, which were significantly different (P < 0.01). The rate of actinomyces-like organisms infection was significantly higher in women wearing IUD for more than seven years. Whereas the occupation or age of women did not affect the detection rate significantly.

Actinomyces↗