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Biomedical subjects

B Li

Publications and source records attributed to B Li.

At least 415 records · Page 23Linked to original sources
PubMed1998

Self-gelatinizable copolymer immobilized glucose biosensor based on prussian blue modified graphite electrode.

A novel poly(vinyl alcohol) grafting 4-vinylpyridine self-gelatinizable copolymer was adapted to immobilize glucose oxidase. The reduction of hydrogen peroxide (H2O2) was detected at a Prussian Blue (PB) modified graphite electrode. A stable and sensitive glucose amperometric biosensor is described. The copolymer is a good biocompatible polymer in which the glucose oxidase retains high activity. Moreover, the copolymer can adhere firmly to the inorganic PB membrane. The sensor showed an apparent Michaelis-Menten constant of 18 +/- 0.2 mM and a maximum current density of 1.14 microA cm-2 mM-1. The linear range is from 5 microM to 4.5 mM glucose and the detection limit is 0.5 microM glucose. The catalytic efficiency of PB for the reduction of H2O2 is higher than that for the oxidation of H2O2. Glucose concentrations in serum samples from healthy persons and diabetic patients were determined using the sensor. The results compared well with those provided by the hospital using a spectroscopy method.

Biosensing Techniques↗
PubMed1998

[Direct-current treatment of chemically induced mammary carcinoma in an animal model: MR volumetric assessment of the effect of the therapy].

PURPOSE: To investigate the effect of direct current treatment (DCT) on the growth of mammary carcinomas in rats by MR-volumetry. METHODS: Chemically induced mammary adenocarcinomas in a control group (n = 17) were compared with treated tumours (18 C/cm3 in group A: n = 7 or 36 C/cm3 in group B: n = 12). 31 untreated tumours were situated near a treated tumour (group C). Experiments were carried out using one positive electrode in the tumour centre and three negative electrodes in the periphery. The tumour volume was measured by MRI before, and 1, 3, 6, 9 and 12 weeks after treatment. RESULTS: 12 weeks after DCT, the mean tumour volume in group A (164% +/- 158%, p < 0.05) and group B (13% +/- 24%, p < 0.001) was significantly reduced compared to the control group (434% +/- 230, Mann-Whitney U-Test). Complete tumour regression occurred in 42% of tumours in group B and was not achieved in group A, C and control group. Tumour growth in group C was decreased compared to the control group. CONCLUSIONS: The effectiveness of DCT was found to depend on the applied dosage -36 C/cm3 was more effective than 18 C/cm3. The effect of DCT is not limited to the area between the electrodes.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1998

A novel method for selection of chymotrypsin inhibitors from a phage peptide library.

A novel screening strategy has been developed for the identification of alpha-chymotrypsin inhibitors from a phage peptide library. In this strategy, the standard affinity selection protocol was modified by adding a proteolytic cleavage period to avoid recovery of alpha-chymotrypsin substrates. After four cycles of selection and further activity assay, a group of related peptides were identified by DNA sequencing. These peptides share a consensus sequence motif as (S/T)RVPR(R/H). Then, a corresponding short peptide (Ac-ASRVPRRG-NH2) was synthesized chemically and proved to be an inhibitor of alpha-chymotrypsin. The present work provides a useful way for searching proteinase inhibitors without detailed knowledge of the molecular structure.

Bacteriophages↗
PubMed1998

Numeric aberration of chromosome 17 is strongly correlated with p53 overexpression, tumor proliferation and histopathology in human bladder cancer.

BACKGROUND: This study investigated the relationships between the numeric aberrations of chromosome 17 and p53 expression, the proliferating cell nuclear antigen labeling index (PCNA-LI) and histopathology, to determine their prognostic significance in bladder cancer. METHODS: Using in situ hybridization (ISH) with a biotin-labeled chromosome-specific DNA probe, the copy number of pericentromeric sequences in chromosome 17 were detected within interphase nuclei in formalin-fixed paraffin-embedded sections from 59 nonmetastasized transitional cell carcinomas (TCCs) of the urinary bladder. Expression of p53 and PCNA-LI were determined in serial sections by an immunohistochemical method. RESULTS: The percentage of hyperdiploid cells for chromosome 17 correlated with p53 overexpression (P< 0.002), PCNA-LI (P< 0.002), increasing tumor grade (P< 0.002) and advanced pathologic stage (P< 0.002). The average percentage of hyperdiploid cells was lower in tumors with negative p53 expression than in tumors with p53 overexpression (P< 0.002). Also, more polysomic TCCs were found in muscle-invasive than in superficial cases (P< 0.01 ), and there was a difference in both p53 overexpression or PCNA-LI between disomic and polysomic TCCs (P< 0.01). Patients with chromosome 17 disomic tumors showed less frequent tumor progression than patients with polysomic tumors (P< 0.05). However, chromosome 17 polysomy was an independent prognostic indicator only for patient survival (P< 0.05). CONCLUSION: The occurrence and extent of numeric aberrations of chromosome 17 may be associated with the evolution of aggressive growth in TCC and may be a useful indicator for survival.

Aged↗
PubMed1998

Differential expression of hepatocyte growth factor in papillary and nodular tumors of the bladder.

BACKGROUND: The aim of this study was to investigate the expression of hepatocyte growth factor (HGF) and its receptor (c-met) during bladder tumorigenesis. METHODS: HGF and c-met expression were analyzed immunohistochemically in matched samples of normal, dysplastic, and carcinoma specimens from 49 human bladders resected at the time of radical cystectomy for nonmetastatic transitional cell carcinoma (TCC). The tumors were composed of papillary (n = 22), nodular (n = 16) or mixed papillary and nodular (mixed; n = 11) components. RESULTS: The normal urothelium showed no significant immunoreactivity to HGF. Expression of HGF was observed in 45.5%, 77.3% and 90.9% of specimens demonstrating mild, moderate, and severe dysplastic lesions adjacent to papillary TCCs, respectively, whereas all of the papillary TCC samples were positive for HGF. No immunoreactivity for HGF was found in dysplastic lesions from nodular tumors, and only 2 specimens had positive immunostaining for HGF in the tumor areas (1 showed weak immunostaining and 1 showed HGF immunostaining only in the deeper invasive compartment). Additionally, 3 nodular lesions taken from mixed tumors showed weak immunostaining for HGF while the concurrent papillary lesions were HGF-positive. There was a significant difference of HGF immunoreactivity between papillary and nodular tumors (P < 0.01). c-met immunostaining was consistently detected in all specimens. HGF and c-met immunoreactivity did not significantly correlate with tumor stage and grade, nor with overall patient survival irrespective of the tumor growth pattern. CONCLUSION: These results suggest that HGF expression may play a significant role in the development of papillary TCC.

Aged↗
PubMed1998

Gene cloning and characterization of a novel cellulose-binding beta-glucosidase from Phanerochaete chrysosporium.

Analysis of a 2.4-kb cDNA of the cellulose-binding extracellular beta-glucosidase (CBGL) from Phanerochaete chrysosporium suggested that CBGL is organized into two domains, an N-terminal cellulose-binding domain and a C-terminal catalytic domain. Genomic sequence analysis suggested that cbgl is encoded by 30 exons. Southern analysis of DNA from homokaryotic cultures indicated that CBGL is encoded by two alleles, cbgl-1 and cbgl-2, of a single gene.

Alleles↗
PubMed1998

Update on Pneumocystis carinii f. sp. hominis typing based on nucleotide sequence variations in internal transcribed spacer regions of rRNA genes.

Pneumocystis carinii f. sp. hominis isolates from 207 clinical specimens from nine countries were typed based on nucleotide sequence variations in the internal transcribed spacer regions I and II (ITS1 and ITS2, respectively) of rRNA genes. The number of ITS1 nucleotides has been revised from the previously reported 157 bp to 161 bp. Likewise, the number of ITS2 nucleotides has been changed from 177 to 192 bp. The number of ITS1 sequence types has increased from 2 to 15, and that of ITS2 has increased from 3 to 14. The 15 ITS1 sequence types are designated types A through O, and the 14 ITS2 types are named types a through n. A total of 59 types of P. carinii f. sp. hominis were found in this study.

Base Sequence↗
PubMed1998

Effect of endotoxin on cytokine production and cell dynamics in mice.

Previous studies have shown that endotoxin potentiates immune responses by direct stimulation of B cells and macrophages. In the present study, we assessed the ability of endotoxin to stimulate cells from different lymphoid tissue compartments to release cytokines. The in vitro stimulation of macrophages with endotoxin resulted in the production of IL-1 and TNF-alpha in a dose and time-dependent manner. Endotoxin also induced the production of IL-2, IFN-gamma and IL-4 secretion in a dose dependent manner in cultured spleen, mesenteric lymph nodes and Peyer's patches cells. The intraperitoneal administration of endotoxin in mice resulted in the accumulation of leucocytes in the peritoneal cavity and in the increase of IL-1, IL-6, TNF-alpha and IFN-gamma concentration in serum. In conclusion, this study confirmed that endotoxin possesses immunomodulatory activities capable of stimulating immune functions both in vitro and in vivo.

Animals↗
PubMed1998

Expression of c-MET/HGF receptor mRNA and protein in human non-malignant and malignant prostate tissues.

We previously reported the expression of hepatocyte growth factor (HGF), a ligand for c-MET, at the level of mRNA and protein in human prostate tissues. The present study was carried out to evaluate the relationship between c-MET expression and cancer cell proliferation or effect of cancer therapy. The expression both in mRNA and protein levels of c-MET proto-oncogene was determined semi-quantitatively by reverse transcription-competitive polymerase chain reaction (RT-competitive PCR) and Western blot analysis for prostate tissues from 32 Japanese male subjects. In addition, tissue localization of c-MET translation product was examined by immunohistochemistry for corresponding specimens. Although there was significantly higher c-MET protein expression in malignant (prostate cancer treated with/without neoadjuvant endocrine therapy) than in non-malignant prostate tissues (normal prostate and benign prostate hyperplasia; BPH), unexpectedly, c-MET mRNA showed high expression in the non-malignant group. Thus, there was no parallelism between mRNA and protein expressions of c-MET. Endocrine therapy did not alter c-MET mRNA and protein expressions in human prostate cancer. Immunohistochemical localization and expression of c-MET protein was found to be intense in cancer cells and weak in epithelia of normal and hyperplastic prostates. Unconcerted expression of mRNA and protein of c-MET, the reason of which is uninterpretable, is supposed to be one of characteristics of human prostate cancer.

Aged↗
PubMed1998

[[symbol: see text]-shaped splitting of spinous process for lumbar spinostenosis].

In order to modify the plastic operation for lumbar spinostenosis, [symbol: see text]-shaped splitting of spinous process was designed. Fifty-six patients with lumbar spinostenosis were treated. There were 36 males and 16 females, age ranged from 32-67 years old (with an average of 48.9 years old). Among them, 8 patients operation on L2-L5 segments, 16 on L3-L5 segments and 22 patients on L4-L5 segments. After operation, 32 cases were followed up from 8 to 27 months. The results were: 1. The result of operation was excellent in 21 cases, good in 8 fair in 2 and poor in 1. The effective rate was 90.6%. 2. The rate of bony union from laminectomy was 95.1%. 3. The sagittal diameter and transverse diameter of the spinal canal were enlarged in an average of 6.4 mm and 3.2 mm, respectively, with a mean enlargement of 37.6%. The conclusion were that the plastic operation with [symbol: see text]-shaped splitting of spinous process for lumbar spinal canal was easy to handle and it could effectively prevent the lumbar instability and secondary stenosis following operation.

Adult↗
PubMed1998

[Relationship between plasma NO and PaO2 of artery blood in the patients with chronic pulmonary heart disease].

The plasma nitric oxide(NO) level in the 28 patients with chronic pulmonary heart disease and health controls were measured. The results showed that NO level in the exacerbating patients and stable patients was significantly lower than that in health controls. The NO level in the patients getting worse was markedly lower than that in the stable patients. The lower the oxygen pressure of the artery blood (PaO2), the lower the NO level. when the patient's situation was improving, the plasma NO level increased with rising PaO2. The plasma NO level in patients was associated with the PaO2. This study suggests that the sustained pulmonary hypertension caused by chronic hypoxia may relate to the reduction of NO synthesis and release, and that NO may play an important role in the pathogenesis in chronic pulmonary heart disease.

Aged↗
PubMed1998

[The effect of partial hepatectomy and portal vein occlusion on aminopyrine metabolism capacity of the liver in rats].

To observe the variation of metabolic function and anatomical weight of the liver after partial hepatectomy and occlusion of portal branches feeding the same magnitude of the liver lobes, hepatic 14C-aminopyrine demethylation capacity determined by aminopyrine breath test and liver weight in rats were examined and compared in series in this study. The results showed that 14CO2 expiratory clearance rate was reduced by 50% at 2 hours and by 70% at 24 hours after 70% hepatectomy. Then it increased gradually and was similar to the preoperative level in 2 weeks. The remnant liver weight was lowest at 2 hours and increased to 80% of the control in 7 days after 70% hepatectomy. It recovered to normal in 2 weeks. In 90% hepatectomy group, 14CO2 expiratory clearance rate decreased by 90% at 2 hours after operation. Thereafter, all rats died very soon. In the 2 portal vein occlusion groups, 14CO2 expiratory clearance rate had little change at 2 hours and it declined by about 40% at 24 hours after ligation of portal branches feeding 70% or 90% liver mass. It recovered gradually and returned to the preoperative level in 2 weeks. The total liver weight in 2 portal occlusion groups was not significantly different from that in the control except that it was slightly lower than the control at 24 hours after operation. This experimental study suggests that comparing deprivation of portal blood feeding partial liver mass with corresponding partial hepatectomy, the former can not only keep the anatomical liver weight relatively stable but also produce a lesser damage to hepatic metabolic function.

Aminopyrine↗
PubMed1998

[Mutation analysis of the p15 gene exon 2 in human primary hepatocarcinoma].

To investigate the role p15 gene plays in the pathogenesis of human primary hepatocarcinoma, 35 human hepatocarcinomas, 35 cases of adjacent non-cancerous liver cirrhosis and the blood cells of 10 normal human were analyzed for somatic mutation in p15 gene with PCR-SSCP. One case of adjacent non-cancerous liver cirrhosis showed abnormal migration single strand. In the hepatocarcinomas and in the other cases of adjacent non-cancerous liver cirrhosis, no mutation was found. Cloning and sequencing of the amplified abnormal migration single strand DNA revealed that it contained a wild type exon 2 of p15 gene in 345 bp length. The results indicate that the inaction of p15 gene by point mutation is a very uncommon event in human hepatocarcinoma.

Carcinoma, Hepatocellular↗
PubMed1998

[The inhibitory effect of wild-type p53 gene on the growth and proliferation of lingual squamous cell carcinoma cell line Tca8113 in nude mice].

The aim of this study was to observe the growth and proliferation of the Tca8113 cell line in nude mice after the wild-type p53 gene has been transfered by electroporation. The experiment consisted of four groups: the wild-type p53 gene, blank control plasmid, the mutant p53 gene, and blank control into which no gene was transfered. After the gene was transfected, the cells were planted into 16 nude mice respectively. When the tumor formed, the nude mice were killed and the tumors were studied by regular pathology, stereology and immunohistochemistry. The results showed that in the wild-type p53 gene group, the tumors weighed less heavy, the pathological mitosis decreased markedly, and stereologically, the ratio of the area of necrosis to the total tumorous area was smaller. Similarly, the count of the proliferation cell nuclear antigen in non-necrotic area went down. The above findings were statistically significant (P < 0.05). These indicate that when the tumor cells re-obtain the well functional exogenic wild-type p53 gene, the gene expresses and produces new negative cell-growth regulator to replace the abnormal regulation system partially, then the growth and proliferation of the tumors can be inhibited; therefore, it is suggested that the p53 tumor suppressor gene may possibly be used as a gene therapy agent to treat oral squamous cell carcinoma.

Animals↗
PubMed1998

[Expression of signal-regulatory protein alpha (SIRP alpha) in hepatocellular carcinoma].

OBJECTIVE: To investigate the association between signal-regulatory protein alpha (SIRP alpha) and hepatocellular carcinoma (HCC). METHODS: Thirty-six pairs of HCC and the surrounding noncancerous hepatic tissues, one normal liver cell line and 4 HCC cell lines were used to extract the total RNA and then to prepare the mRNA. The expression of SIRP alpha was determined by Northern blot analysis. The results were analyzed in association with the pathologic characteristics of each sample. RESULTS: SIRP alpha expressed at low level in 20 of 36 HCC samples and 2 of 4 HCC cell lines. Of the two major hybridization signals, a 3.9 kb transcript in HCC samples was 2-4 times lower than that in the surrounding noncancerous hepatic tissues, whereas a 2.5 kb transcript was 4-6 times as low. Furthermore, a hybridization signal slightly longer than 3.9 kb, being absent in the surrounding noncancerous hepatic tissue, appeared in 9 of the 20 HCC samples. Low level expression of SIRP alpha was observed in all of the 5 HCC samples that had intrahepatic or portal metastasis. CONCLUSION: The expression of SIRP alpha, especially 2.5 kb transcript, was down-regulated in HCC, and an unknown mumber or a variant of SIRP family existed in some tumor tissues. SIRP alpha protein may play an important role in hepatic oncogenesis and metastasis of HCC.

Antigens, Differentiation↗
PubMed1998

[Diagnosis and endovascular treatment of multiple thrombosis in cerebral venous sinus].

OBJECTIVE: To study 12 cases of multiple thrombosis in cerebral venous sinuses and the diagnosis and endovascular therapy. METHOD: The long T2 and short T1 signals in the related region of multiple venous sinuses on MR were important characteristics for the diagnosis before angiography. In the 12 cases, the treatment consisted of intermittent injection of urokinase via common carotid artery and oral administration of warfarin. RESULTS: Intracranial pressure of 11 cases reduced to lower than 300 mm H2O and clinical deficits were markedly improved in 10 days. Re-angiography of 4 cases found partial recanalization in 2 in one week after therapy. CONCLUSION: Intraoarterial thrombolysis combined with general anticoagulation in the treatment of multiple thrombosis in cerebral venous sinuses may be an effective meansure.

Adolescent↗
PubMed1998

[The effect of palate repair on middle ear function].

By means of acoustic impedance and otoscopic examinations the middle ear function and incidence of secretory otitis media (SOM) were demonstrated in 43 cases of cleft palate children pre- and post palatal closure. The results showed that 61.36% of the 86 ears had SOM prior to palatal closure and there was no difference between cleft types (P > 0.05). The patient with the age of 9 years or less have higher incidence of SOM than the older ones (P < 0.05). The study indicated that the middle ear status can be improved by palatal surgery for the cleft palate children.

Adolescent↗