Biomedical subjects

L Pan

Publications and source records attributed to L Pan.

At least 91 records · Page 5Linked to original sources

PubMed1999

Expression of endothelial cell IgG Fc receptors and markers on various cultures.

OBJECTIVE: To determine and compare the expression of endothelial cell IgG Fc receptors (Fc gamma R) and markers on various kinds of cultures. METHODS: Human breast microvascular endothelial cells (HMVEC), human aortic endothelial cells (HAEC), human umbilical vein endothelial cells (HUVEC) and canine aortic endothelial cells (CAEC) were stimulated with cytokines tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma). The binding of anti-Fc gamma receptor (Fc gamma R) type I, II and III antibodies was measured using an enzyme-linked immunosorbent assay (ELISA). The constitutive expression of endothelial cell markers was examined using anti-von Willebrand factor antibodies, Dil-low density lipoprotein (Dil-Ac-LDL) and fluorescein isothiocyanate (FITC)-labeled ulex europaeus agglutinin-1. RESULTS: The binding of anti-Fc gamma R II was significantly increased by the simultaneous stimulation with TNF-alpha and IFN-gamma on all three types of human endothelial cells (ECs), but not on canine endothelial cells. Enhanced Fc gamma R II expression was most significant when human ECs were cultured in endothelial cell basal medium (ECBM). However, the expression of Fc gamma R II on CAECs could not be induced by human cytokines even after they were cultured in ECBM for 3 passages. Endothelial cells also showed diversity for the constitutive expression of classic markers. CONCLUSIONS: This study demonstrate that cytokines TNF-alpha and IFN-gamma enhance low-affinity Fc gamma R expression on human endothelial cells in vitro. The results indicate that heterogeneity of endothelial cells exists not only on constitutive expression but also on stimulative expression.

Animals↗

PubMed1999

[Morphological cure of cerebral arteriovenous malformations by endovascular therapeutics].

OBJECTIVE: To sum up the clinical characteristics and typical manifestation by analysing clinical materials from total embolized cerebral arteriovenous malformations (AVM) via endovascular embolization. METHODS: We reviewed clinical and image materials of 50 patients whose cerebral AVM were embolized entirely and found the cerebral AVM morphological cure by endovascular embolization after studying the size, position, artery supply, therapeutics and follow-up. RESULTS: 50 patients with cerebral AVM were embolized by endovascular therapy, accounting for 17% of all patients. Malformation lesions were medium or small type, with a diameter less than 3 cm, 95% of them were located in the tentorium superior. Terminal end blood supply was common to AVM and especially medium cerebral artery (MCA) or its branches. 97% of the patients were graded III or below by spectzler grading system. 70% of them had a history of intracranial hemorrhage and were cured by one therapy. CONCLUSIONS: It is a reliable and feasible method for morphological cure in cerebral AVM via endovascular therapeutics only, but case selection is important, that is, medium or small AVM with single branch terminal end blood supply in the tentorium superior.

Adolescent↗

PubMed1999

[A case-control study on Guillain-Barre syndrome in children of North China].

OBJECTIVE: This study aimed at exploring the risk factors for Guillain-Barre syndrome (GBS). METHODS: A case-control study design was used with 51 cases of GBS, diagnosed based on their symptoms, signs and electrophysiological examinations and exclusion of poliomyelitis and other acute flaccid paralysis, and 51 controls matched on age, sex and resident village. Serum IgG antibodies specific for Campylobacter jejuni were determined for all the subjects by enzyme-linked immunosorbent assay (ELISA) with a preparation of surface antigen of C. jejuni C(1) strain isolated from the patients and prevalent in north China. Each case and control were interviewed with his/her parents or guardians by a trained interviewer using an ad hoc questionnaire, including his/her demographic information, socioeconomic status, onset of the illness, and potential risk factors in their environment and personal hygiene. Data were analyzed with SAS software release 6.04 in a microcomputer. RESULTS: GBS was associated with a few factors, such as residential areas (45 of the 51 cases living in the rural areas, accounting for 88.2% of the total), polio and hepatitis B vaccine immunization before onset of the illness (with ORs of 7.27 and 3.14, respectively), no hand washing after defecation and before meals (with an OR of 6.15) and getting cold and going to the river or lake site before onset of the illness (with ORs of 13.75 and 12.20, respectively). Infection with Campylobacter jejuni associated strongly with the illness (with an OR of 9.5, P < 0.001). Thirty-five of the 51 cases had precursor symptoms before onset of the illness (68.6%). CONCLUSION: It suggests that occurrence of GBS may correlate to infection with Campylobacter jejuni and poor personal hygiene in children.

Antibodies, Bacterial↗

PubMed1999

[Roles of bifidobacterium on prevention of experimental colorectal carcinoma and induction of apoptosis].

OBJECTIVE: To explore the effect of bifidobacterium adolescence on prevention from experimental colorectal carcinoma and its antitumor mechanism. METHODS: An animal model of nude mouse tumor transplanted from colorectal carcinoma was set up. Bifidobacteria adolescence were intraperitoneally injected into nude mice in advance. The growth rate, ultrastructure, density of apoptotic cells, rate of bcl-2 and bax oncoprotein expression and its positive cell density in transplanted tumor of nude mice from colorectal carcinoma were investigated by employing transmission microscopy, in situ end labeling technique and immunohistochemical staining. RESULTS: The growth rate of transplanted tumors from colorectal carcinoma in the group with bifidobacterium prevention was slower than that in the control group. Many tumor cells at varied apoptotic stages could be observed in transplantation tumor tissue in the bifidobacterium prevention group and their density of apoptotic cells, rate of bcl-2 and bax oncoprotein expression and its positive cell density were significantly higher in the group with bifidobacterium prevention, as compared with the control group (P < 0.01). But, expression rate of bcl-2 oncoprotein turned contrary to that of bax oncoprotein. CONCLUSION: Bifidobacteria adolescence could markedly prevent from occurrence and development of colorectal carcinoma in vivo and induce apoptosis of tumor.

Animals↗

PubMed1999

[The correlation analysis of obstructive sleep apnea syndrome and the size of oropharyngeal cavity].

OBJECTIVE: To explore the relationship between obstructive sleep apnea syndrome (OSAS) and the size of oropharyngeal cavity. METHOD: The distance from uvula basis to tongue, the distance between anterior and posterior tonsillar pillars and the uvula area were measured for 30 OSAS patients and 30 healthy controls. RESULT: The study data indicated that there was very significant difference between patients and healthy controls (P < 0.001). The results of correlation analysis indicated that there was a nagetive correlation between the distance from uvula basis to tongue, the distance from anterior to between posterior tonsillar pillars and apnea hypopnea index (AHI) (P < 0.05), but there was a positive correlation between uvula area and AHI (P < 0.01). The patient's height, weight were measured, the body mass index was positive correlation with AHI (P < 0.001). CONCLUSION: These observations suggest that the obesity, smaller pharyngerl area can play an important role in the pathogenesis of OSAS.

Adult↗

PubMed1998

High frequency of CagA+ Helicobacter pylori infection in high-grade gastric MALT B-cell lymphomas.

A high incidence of Helicobacter pylori infection has been found in patients with gastric MALT (mucosa-associated lymphoid tissue) B-cell lymphoma. Recent studies have indicated that the aggressive strains of the bacterium containing the CagA gene may have direct effects on tumourigenesis. To investigate the involvement of CagA+ strains in MALT lymphomagenesis, a sensitive polymerase chain reaction (PCR)-based detection assay for the gene was developed. DNA extracts from paraffin sections of 123 H. pylori-related gastric biopsies from Italy were analysed, including 56 cases of chronic gastritis, 37 low-grade, and 30 high-grade MALT lymphomas: 30.3 per cent (17/56) of the gastritis cases, 37.8 per cent (14/37) of the low-grade, and 76.7 per cent (23/30) of the high-grade MALT lymphomas were found to contain the CagA gene. The frequency of CagA+ strain infection was significantly higher (P < 0.05) in high-grade than in low-grade MALT lymphoma or gastritis. These results suggest that high-grade gastric MALT lymphoma transformation may be more likely to occur following infection by CagA+ strains of H. pylori.

Antigens, Bacterial↗

PubMed1998

Infrequent bax gene mutations in B-cell lymphomas.

Mutation of the bax gene has been reported previously in lymphoid cell lines. In vitro experiments have shown that alterations in promoter and coding sequences of the gene abolish its apoptosis initiation function, which is considered crucial for tumour development. To assess bax gene mutations in lymphomagenesis, polymerase chain reaction-based single strand conformation polymorphism analysis (PCR-SSCP) and direct sequencing were used to detect altered sequences in the promoter region and all the six exons and their flanking sequences of the gene. Nodal and extranodal B-cell lymphomas (n = 112) including follicular lymphoma, mantle cell lymphoma, diffuse large B-cell lymphoma, splenic marginal zone B-cell lymphoma and low- and high-grade mucosa-associated lymphoid tissue (MALT) lymphomas were studied. Sequence alterations were found in 11 cases. Nine also showed the same altered sequences in corresponding non-tumour control tissue samples, indicating polymorphism. In the remaining two cases, sequence alterations (in exons 3 and 6) which altered the bax open reading frame were observed only in tumour tissues, indicating tumour-specific point mutation. These results suggest that inhibition of apoptosis through bax gene mutations is unlikely to be a common event in B-cell lymphoma, at least in the major types of nodal and extranodal B-cell lymphomas.

DNA, Neoplasm↗

PubMed1998

Ultrasonic and viscoelastic properties of skin under transverse mechanical stress in vitro.

Ultrasound properties of rabbit and human skin tissues under transverse stress have been studied in vitro over the frequency range from 15 MHz to 40 MHz. B-scan images show significant increases in average dermal grey-scale levels for increasing strain. Quantitative measurements show that ultrasound attenuation coefficients decrease significantly with increasing strain. A linear decrease of 0.109 dB/mm/strain% in rabbit skin and 0.069 dB/mm/strain% in human breast reduction skin was observed at 30 MHz. Experimental results show that backscattering coefficients only exhibit minor variation with strain. The speed of sound in human skin appears to be age-dependent. The viscoelastic and mechanical properties of skin, including stress relaxation, creep and Young's modulus as a function of strain were also studied.

Animals↗

PubMed1998

Comparison of two high-performance liquid chromatographic methods for monitoring plasma concentrations of haloperidol and reduced haloperidol.

Two high-performance liquid chromatographic methods for monitoring haloperidol (HAL) and reduced haloperidol (RHAL) plasma concentrations were compared. In one method ultraviolet detection and a C18 column were used (UV method); in the other method electrochemical detection and a CN-column were used (EC method). Both methods are accurate and precise. For plasma samples spiked with HAL or RHAL, an excellent correlation was observed between the concentrations of HAL and RHAL found with both methods (r < or = 0.99, p < 0.01). However, for plasma obtained from patients treated with HAL the correlation between the two methods was poor (r > or = 0.71, p < 0.01). The main reason for the discrepancy between the two methods is probably interference of comedications or their metabolites, mostly in the EC method. Although the quantitation limit of the UV method (2 ng/ml for HAL and RHAL) is higher than that of the EC method (0.5 ng/ml for HAL and RHAL), the UV method is to be preferred for monitoring plasma levels in psychiatric patients because there is less interference from comedication.

Administration, Oral↗

PubMed1998

Functional replacement of the mouse E2A gene with a human HEB cDNA.

The mammalian E2A, HEB, and E2-2 genes encode a unique class of basic helix-loop-helix (bHLH) transcription factors that are evolutionarily conserved and essential for embryonic and postnatal development. While the structural and functional similarities among the gene products are well demonstrated, it is not clear why deletion of E2A, but not HEB or E2-2, leads to a complete arrest in B-lymphocyte development. To understand the molecular basis of the functional specificity between E2A and HEB/E2-2 in mammalian development, we generated and tested a panel of E2A knockin mutations including subtle mutations in the E12 and E47 exons and substitution of both E12 and E47 exons with a human HEB cDNA. We find that the alternatively spliced E12 and E47 bHLH proteins of the E2A gene play similar and additive roles in supporting B lymphopoiesis. Further, we find that HEB driven by the endogenous E2A promoter can functionally replace E2A in supporting B-cell commitment and differentiation toward completion. Finally, the postnatal lethality associated with E2A disruption is fully rescued by the addition of HEB. This study suggests that the functional divergence among E12, E47, and HEB in different cell types is partially defined by the context of gene expression.

Alleles↗

PubMed1998

Pituitary adenomas: the effect of gamma knife radiosurgery on tumor growth and endocrinopathies.

Seventy-three patients have been treated with Gamma Knife radiosurgery (GKR) for pituitary adenomas. 12 had undergone surgery prior to GKR. Three had had previous radiation therapy. The prescription dose administered to the tumor margin ranged from 9 to 35 Gy. 65 patients were followed up for an average of 29 months. A slight expansion of tumor volume occurred in 3 cases. Otherwise, the tumor volume remained unchanged or decreased in the remainder. Endocrine changes were present in all except 3 cases. GKR was followed by a speedy decrease in raised serum hormone levels in the case of both growth hormone (GH)and adrenocortico-tropic hormone (ACTH). In 3 patients there was some visual deterioration associated with a slight increase in tumor volume. In 2 cases, the tumors were removed surgically. Some preliminary conclusions may be drawn. The dose required to correct an endocrinopathy may be higher than that required for control of tumor growth. The recommended prescription dose for endocrine-active adenomas may be more than 30 Gy. While clinical improvement may be noted in patients with raised serum prolactin levels (PRL), normalization of the endocrinopathy may be less readily achieved than in the case of raised GH and ACTH levels. Gamma Knife radiosurgery as a primary treatment of pituitary adenomas can be safe and effective.

Adenoma↗

PubMed1998

Gamma knife radiosurgery for hemangioblastomas.

Thirteen patients (11 males, 2 females) with cerebral hemangioblastomas (HABs) were treated with Gamma Knife radiosurgery (GKR). Four patients had multiple lesions in the brain. The remainder had a single lesion. The total number of lesions was 20. Eight cases had recurrent or residual HABs after surgery. In one case diagnosis was confirmed following surgical resection 22 months after GKR. One case was diagnosed by computed tomography (CT), magnetic resonance imaging (MRI) and digital subtraction angiography (DSA). Three patients had von Hippel Lindau (VHL) disease. The mean tumor diameter was 20 mm (range 7.5 to .55 mm). The mean margin dose was 18 Gy (range 12 to 24 Gy). In 5 cases, there was an improvement of symptoms and reduction in tumor volume. In 4 cases the tumor volume and clinical status remained unchanged. In 3 patients, there was clinical deterioration. The cause of this was an increase in tumor cyst volume in 2 cases. Subsequent surgery resulted in clinical improvement. In a third patient with multiple lesions, deterioration was the result of adverse radiation effects in the medulla oblongata. Three patients were subjected to post GKR-surgery with subsequent histopathology. In one, this was due to cyst expansion. In one, it was at the patient's insistence in the presence of a stable clinical and radiological picture. In a third patient with a temporal lobe tumor, it was because of late-developing epileptic seizures. The histopathological findings in these patients showed varying degrees of small vessel thickening and occlusion together with loss of tumor cells. The observations varied in degree according to the time between GKR and the secondary operation. These findings indicate the effectiveness of the treatment. The reduction in vascularity suggests that GKR could make subsequent surgery less hazardous. The observations of this study suggest that while GKR is not adequately reliable for the control of HAB cysts, it can be an effective treatment for solid tumors, especially those in eloquent regions.

Adolescent↗

PubMed1997

Total body irradiation and acute graft-versus-host disease: the role of gastrointestinal damage and inflammatory cytokines.

The influence of bone marrow transplantation (BMT) conditioning regimens on the incidence and severity of graft-versus-host disease (GVHD) has been suggested in clinical BMT. Using murine BMT models, we show here an increase in GVHD severity in several donor-recipient strain combinations after intensification of the conditioning regimen by increasing the total body irradiation (TBI) dose from 900 cGy to 1,300 cGy. Increased GVHD was mediated by systemic increases in tumor necrosis factor alpha (TNF alpha). Histologic analysis of gastrointestinal tracts showed synergistic damage by increased TBI and allogeneic donor cells that permitted increased translocation of lipopolysacharide (LPS) into the systemic circulation. In vitro, LPS triggered excess TNF alpha from macrophages primed by the GVH reaction. In addition, macrophages isolated within 4 hours of conditioning were primed in proportion to the TBI dose itself to secrete TNF alpha. Thus, the higher TBI dose increased macrophage priming and increased gut damage after allogeneic BMT, causing higher systemic levels of inflammatory cytokines and subsequent severe GVHD. These data highlight the importance of conditioning in GVHD pathophysiology and suggest that interventions to prevent LPS stimulation of primed macrophages may limit the severity of GVHD after intensive conditioning for allogeneic BMT.

Animals↗

PubMed1997

Trauma-induced striatal CNTF and BDNF mRNA in hemiparkinsonian rats.

Surgical implantation of tissues into the brain causes trauma to the region receiving the graft. This study shows that real or simulated striatal trauma in hemiparkinsonian rats leads to increased expression of two trophic factor mRNAs: ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF). The baseline expression of BDNF mRNA was also markedly lower in dopamine-depleted striatum than in normal striatum in non-traumatized (control) hemiparkinsonian rats. Striatal CNTF message was relatively symmetrical in the non-traumatized (control) hemiparkinsonian rats. Host production of these and other trophic factors may play important roles in the response to tissue grafting, to enhance graft survival and as a stimulus to regenerative collateral axonal sprouting.

Animals↗

PubMed1997

Clonality analysis in tumours of women by PCR amplification of X-linked genes.

Modifications have been made to two polymerase chain reaction (PCR) methods for clonality analysis based on the inactivation patterns of two highly polymorphic X-linked genes encoding the androgen receptor (AR) and monoamine oxidase A (MAOA). These methods have been used to examine the clonal nature of frozen tissues from 42 tumours and 25 non-tumour controls from female subjects. Unbalanced inactivation patterns of the genes, which indicate monoclonality, were frequently observed in tumours of heterozygous (informative) cases (18/35 = 51.4 per cent for the AR gene, 9/30 = 30 per cent for the MAOA gene, and 21/38 = 55.2 per cent for both). Among 23 informative non-tumour controls, only one (4.3 per cent), a reactive lymph node, showed skewing in the AR gene. Successful detection of monoclonality was found to depend on the proportion of tumour cells in the tissues examined. None of the AR or MAOA informative cases containing less than 50 per cent of tumour cells showed imbalance in inactivation patterns. With more than 50 per cent of tumour cells in the samples, 66.6 per cent (18/27) of AR and 39.1 per cent (9/23) of MAOA informative cases showed allelic imbalance, with a combined frequency of 72.4 per cent (21/29) of both genes. Our results demonstrate that the methods described are useful for clonal analysis of tissue samples from female patients.

Breast Neoplasms↗

PubMed1997

c-myc gene abnormalities in mucosa-associated lymphoid tissue (MALT) lymphomas.

c-myc gene abnormalities associated with lymphomagenesis, including rearrangements and mutations in the regulatory region between exon I and intron I, have been studied in 54 MALT lymphomas (43 low and 11 high grade) and 36 nodal lymphomas (27 low and 9 high grade). By Southern blot analysis, none of the 54 MALT lymphomas but 2 of 36 nodal lymphomas had c-myc gene rearrangements. Defined tumour cell populations from all MALT lymphoma cases were isolated by microdissection from frozen tissue sections and analysed by polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) and direct sequencing for somatic mutations in the exon I/intron I region of the gene. Point mutations in this region were identified in nine cases of MALT lymphomas (7/43 = 16.2 per cent of low grade; 2/11 = 18.1 per cent of high grade). These mutations were located at either the exon I/intron I border of myc intron factor (MIF) binding sites, which are critical in the negative regulation of c-myc expression. Of the nodal lymphomas, only the two cases (5-6 per cent) with c-myc gene rearrangement showed scattered or clustered mutations. These results suggest that c-myc mutations in MALT lymphomas are unlikely to be associated with chromosome translocation, which is the main cause of somatic mutations observed in other types of lymphomas. The mutations involving the c-myc regulatory regions may play a pathogenetic role in at least a proportion of MALT lymphomas.

Base Sequence↗

PubMed1997

Genetic evidence for a clonal link between low and high-grade components in gastric MALT B-cell lymphoma.

High-grade MALT lymphomas often contain low-grade tumour components; both cell populations have been shown to express the same immunoglobulin light chain previously. However, the clonal link between the low and high-grade components has not been established at the genetic level. To investigate this link, we have examined low- and high-grade components micro-dissected from tissue sections of four high-grade gastric MALT lymphomas. PCR and sequence analyses were performed to identify clone-specific rearranged immunoglobulin heavy chain gene sequences. In each of these cases, the PCR products from the two components were identical in size by electrophoresis. Direct sequencing revealed common clone-specific immunoglobulin heavy chain gene rearrangements in both lesions of each case, providing genetic evidence for a clonal link. These results support the proposal that high-grade MALT lymphomas generally evolve from low-grade clones.

Base Sequence↗

PubMed1997

[Sequence alterations in p53 gene of hepatocellular carcinoma from high aflatoxin risk area in Guangxi].

OBJECTIVE: Check on the sequence alterations of the p53 gene of hepatocellular carcinoma (HCC) in some areas of Guangxi. METHODS: 40 cases of archival HCC samples were divided into two groups. One includes 26 cases from Fusui--an area notorious for high risk in HCC, AFB1 and HBV; The other includes 14 cases from Yulin where both HCC and HBV were high but AFB1 may be low because rice low in AFB1 was the staple food. Exon 7 were sequenced by DNA direct sequencing. p53 mutational protein and HBsAg were examined by immunostaing. RESULTS: In the Fusui group, 16/26 (61.5%) cases showed mutation at codon 249 third position G to T transversion to form a hot-spot which is generally considered to be caused by AFB1. In the Yulin group, only one single place-Guigang showed p53 mutation clustered at the hot-spot like Fusui in 3/5 cases (60%), while the other cases demonstrated mutational points in various positions. CONCLUSION: Besides Qidong and South Africa, a third AFB1 high risk area was demonstrated where HCC is accompanied by p53 gene specific mutation.

Adult↗