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Biomedical subjects

B Lin

Publications and source records attributed to B Lin.

At least 145 records · Page 8Linked to original sources
PubMed1997

Alteration of acidic lipids in human sera during the course of pregnancy: characteristic increase in the concentration of cholesterol sulfate.

In this study, we determined the concentrations of acidic lipids, including cholesterol sulfate (CS), sulfatide and GM3 ganglioside, in human sera of non-pregnant state and during the course of pregnancy. In human sera of non-pregnant women, GM3 was present at a concentration of 8 nmol/ml and the concentrations of CS and sulfatides were less than 20% of that of GM3. The concentration of sulfatides in sera at the second trimester of gestation was decreased, but CS gradually increased from the first to the third trimester of gestation with a correlation coefficient of 0.66, and a correlation between the concentration of CS and weeks of gestation (p<0.01). CS was also contained in the placental villi, and its concentration increased from the first to the third trimester of gestation, suggesting that placental CS is one of the source of CS in the blood by shedding.

Cholesterol Esters↗
PubMed1997

The role of HNF1alpha, HNF3gamma, and cyclic AMP in glucose-6-phosphatase gene activation.

The gene for glucose-6-phosphatase (G6Pase), the key enzyme in glucose homeostasis, is expressed in a tissue-specific manner in the liver and kidney. To understand the molecular mechanisms regulating liver-specific expression of the G6Pase gene, we characterized G6Pase promoter activity by transient expression assays. The G6Pase promoter is active in HepG2 hepatoma cells, but inactive in JEG3 choriocarcinoma or 3T3 cells. DNA elements essential for optimal and liver-specific expression of the G6Pase gene were contained within nucleotides -234 to +3. Deletion analysis revealed that the G6Pase promoter contained three activation elements (AEs) at nucleotides -234 to -212 (AE-I), -146 to -125 (AE-II), and -124 to -71 (AE-III). AE-I contains binding sites for hepatocyte nuclear factors (HNF) 1 and 4. Electromobility shift and cotransfection assays demonstrated that HNF1alpha, but not HNF4, bound to its cognate site and transactivated G6Pase gene expression. The G6Pase promoter contained five HNF3 motifs, 1 (-180/-174), 2 (-139/-133), 3 (-91/-85), 4 (-81/-75), and 5 (-72/-66), and all five sites bound HNF3gamma with high affinity. Transient expression and cotransfection assays showed that HNF3 site 1 is not required for basal promoter activity, but is essential for HNF3gamma-activated transcription from the G6Pase promoter. We further showed that HNF3 sites 3, 4, and 5 were essential for basal G6Pase promoter activity and transactivation by HNF3gamma. AE-II contains, in addition to a HNF3 motif, a cAMP-response element (CRE) and a C/EBP half-site. The G6Pase(-146/-116) DNA containing AE-II formed multiple protein-DNA complexes with HepG2 nuclear extracts, including HNF3gamma, CRE-binding protein (CREB), C/EBPalpha, and C/EBPbeta. We showed that AE-II mediated transcription activation of the G6Pase gene by cAMP.

Base Sequence↗
PubMed1997

Expression of herpes virus thymidine kinase in Neurospora crassa.

The expression of thymidine kinase in fungi, which normally lack this enzyme, will greatly aid the study of DNA metabolism and provide useful drug-sensitive phenotypes. The herpes simplex virus type-1 thymidine kinase gene ( tk ) was expressed in Neurospora crassa. tk was expressed as a fusion to N.crassa arg-2 regulatory sequences and as a hygromycin phosphotransferase-thymidine kinase fusion gene under the control of cytomegalovirus and SV40 sequences. Only strains containing tk showed thymidine kinase enzyme activity. In strains containing the arg-2 - tk gene, both the level of enzyme activity and the level of mRNA were reduced by growth in arginine medium, consistent with control through arg-2 regulatory sequences. Expression of thymidine kinase in N.crassa facilitated radioactive labeling of replicating DNA following addition of [3H]thymidine or [14C]thymidine to the growth medium. Thymidine labeling of DNA enabled demonstration that hydroxyurea can be used to block replication and synchronize the N.crassa mitotic cycle. Strains expressing thymidine kinase were also more sensitive than strains lacking thymidine kinase to anticancer and antiviral nucleoside drugs that are activated by thymidine kinase, including 5-fluoro-2'-deoxyuridine, 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-iodouridine and trifluorothymidine. Finally, expression of thymidine kinase in N. crassa enabled incorporation of bromodeoxyuridine into DNA at levels sufficient to separate newly replicated DNA from old DNA using equilibrium centrifugation.

Antiviral Agents↗
PubMed1997

Identification of a histidine residue essential for enzymatic activity of group B streptococcal hyaluronate lyase.

Hyaluronate lyase produced by group B streptococci (GBS) degrades hyaluronan completely to unsaturated disaccharide units and also cleaves unsulfated regions of chondroitin sulfate. The enzyme is rapidly inactivated by diethyl pyrocarbonate and enzymatic activity is restored by treatment with hydroxylamine, suggesting that a histidine residue is present in the active site. Amino acid sequence comparisons of GBS hyaluronate lyase and four other related enzymes revealed that one of the 16 histidine residues of the enzyme (His-479) is present in a highly conserved region. Conversion of His-479 to a glycine by site-directed mutagenesis resulted in a complete loss of enzymatic activity of the modified protein. We propose that His-479 is in the active site of GBS hyaluronate lyase and participates in the initial abstraction of hydrogen ions from the glucuronic acid residues of hyaluronan.

Amino Acid Sequence↗
PubMed1997

Inhibition of trans-retinoic acid-resistant human breast cancer cell growth by retinoid X receptor-selective retinoids.

All-trans-retinoic acid (trans-RA) and other retinoids exert anticancer effects through two types of retinoid receptors, the RA receptors (RARs) and retinoid X receptors (RXRs). Previous studies demonstrated that the growth-inhibitory effects of trans-RA and related retinoids are impaired in certain estrogen-independent breast cancer cell lines due to their lower levels of RAR alpha and RARbeta. In this study, we evaluated several synthetic retinoids for their ability to induce growth inhibition and apoptosis in both trans-RA-sensitive and trans-RA-resistant breast cancer cell lines. Our results demonstrate that RXR-selective retinoids, particularly in combination with RAR-selective retinoids, could significantly induce RARbeta and inhibit the growth and induce the apoptosis of trans-RA-resistant, RAR alpha-deficient MDA-MB-231 cells but had low activity against trans-RA-sensitive ZR-75-1 cells that express high levels of RAR alpha. Using gel retardation and transient transfection assays, we found that the effects of RXR-selective retinoids on MDA-MB-231 cells were most likely mediated by RXR-nur77 heterodimers that bound to the RA response element in the RARbeta promoter and activated the RARbeta promoter in response to RXR-selective retinoids. In contrast, growth inhibition by RAR-selective retinoids in trans-RA-sensitive, RAR alpha-expressing cells most probably occurred through RXR-RAR alpha heterodimers that also bound to and activated the RARbeta promoter. In MDA-MB-231 clones stably expressing RAR alpha, both RARbeta induction and growth inhibition by RXR-selective retinoids were suppressed, while the effects of RAR-selective retinoids were enhanced. Together, our results demonstrate that activation of RXR can inhibit the growth of trans-RA-resistant MDA-MB-231 breast cancer cells and suggest that low cellular RAR alpha may regulate the signaling switch from RAR-mediated to RXR-mediated growth inhibition in breast cancer cells.

Antineoplastic Agents↗
PubMed1997

Sleep and gastric function in irritable bowel syndrome: derailing the brain-gut axis.

BACKGROUND: Recently, several studies have shown an alteration in bowel function during sleep in patients with irritable bowel syndrome (IBS), and a recent study also suggests a remarkable increase in rapid eye movement (REM) sleep. These studies have suggested that an alteration in CNS function may play an important role in the pathogenesis of IBS. AIMS: To confirm the presence of an alteration in REM sleep in patients with IBS and to assess the relation between sleep and a non-invasive measure of gastric functioning, the electrogastrogram (EGG). PATIENTS: Ten patients with IBS and 10 age and sex matched normal volunteers. METHODS: All subjects slept one night in the sleep laboratory and underwent polysomnographic monitoring to determine sleep patterns, and recording of the EGG from surface electrodes. RESULTS: The IBS group had a notable and significant increase in the percentage and duration of REM sleep (p < 0.05). The control group had a decrease in the amplitude of the dominant EGG frequency from waking to non-REM sleep (p < 0.05), and a subsequent increase in the amplitude from non-REM to REM sleep (p < 0.05). No such changes were noted in the patients with IBS. CONCLUSIONS: Results confirmed the enhancement of REM sleep in patients with IBS and suggested an intrinsic alteration in autonomic and CNS functioning in patients with IBS.

Adult↗
PubMed1997

The role of the pharmacy department in the prevention of adverse drug events: a survey of current practices.

Adverse drug events have received a great deal of publicity during he past several years. The tracking and prevention of medication errors is an important part of ensuring quality care for patients. The American Society of Health-System Pharmacists, and the Institute For Safe Medication Practices are two groups who have published recommendations on the prevention of adverse drug events in hospitals. This study provides an informative analysis of the status of implementation of these recommendations by hospital pharmacists in Louisiana.

Adverse Drug Reaction Reporting Systems↗
PubMed1997

[Somatostatin in NRM plays roles in inducing analgesia and enhancing electroacupuncture analgesia].

The effects of microinjection of somatostatin (SS), somatostatin depletor cysteamine (CS) and anti-somatostatin serum (ASSS) on the pain threshold (PT) and electroacupuncture (EA) analgesia were investigated in the rat. The potassium iontophoresis induced tail-flick was used to measure the pain threshold. The "Zusanli" were stimulated with EA. The results indicated that microinjection of SS into necleus raphe magnus (NRM), could elevate PT and enhance EA analgesia. PT and EA analgesia were decreased when SS in NRM was depleted by CS or neutralized by ASSS. These data revealed that SS in NRM plays important roles in inducing analgesia and enhancing electroacupuncture analgesia.

Acupuncture Analgesia↗
PubMed1997

[The methylation of CT gene in chronic myeloid leukemia].

To investigate the relationship between the abnormal methylation of the calcitonin (CT) gene and the karyotypic abnormality in predicting the disease progress in chronic myeloid leukemia (CML), we studied the abnormal methylation of the CT gene in 47 CML patients by using a sensitive PCR method. At the same time, cytogenetic study was made in the same group of patients. The abnormal methylation of CT gene was found in only 4 of 24 patients in chronic phase, but in 6 of 9 patients in accelerated phase, and in 12 of 14 patients in blast crisis. Sequential studies in one patient also showed that the gene is normally methylated during the chronic phase but turns hypermethylated as the disease progresses. Our findings indicate that abnormal methylation of the 5' region of the CT gene is regularly a marker of disease progression in CML.

Adolescent↗
PubMed1997

[DNA polymorphism analysis by capillary electrophoresis].

A review is given here to describe the principle and methods of gene polymorphism analysis by capillary electrophoresis (CE). DNA length polymorphism and sequence polymorphism are very important phenomena in gene molecular biology. Some practical works of gene length polymorphism analysis and sequence polymorphism analysis are listed. SSCP and HPA methods detecting gene point mutations are demonstrated. Applications of gene polymorphism analysis by CE in clinical, forensic and biological research are also discussed in this paper.

Animals↗
PubMed1997

Marked differences in proliferative response to stimulation of growth hormone and insulin-like growth factor-I between thymoma- and normal thymus-derived epithelial cell lines.

Two kinds of thymus epithelial cell lines have been utilized: the TAD3 from lymphocyte-dominant rat thymoma and the IT-45R1 derived from normal rat thymus. In the preconfluent state, the percent increase of DNA synthetic activity of TAD3 cells stimulated by GH or IGF-I was significantly higher than that of IT-45R1 cells. In the confluent state, at the contrary, no any noticeable modification of the activity by GH could be detected and that in both cell lines. However, a treatment of the confluent TAD3 cells with IGF-I caused a significant increase of their DNA synthetic activity, whereas the confluent IT-45R1 cells treated with these molecules did not. It was observed that TAD3 cells in the preconfluent state proliferate markedly after stimulation by GH or IGF-I as compared with IT-45R1 cells and that the former is able to proliferate even in the confluent state, after an exposure of IGF-I, whereas the latter did not. Thymus epithelial cells treated with GH were reported to release more IGF-I molecules what had as a consequence a marked proliferative response of thymic lymphocytes. It is therefore assumed that the very particular nature of TAD3 cells treated with IGF-I, able of proliferating by crossing over the contact inhibition, might have a close relationship in the formation of the lymphocyte-dominant thymoma.

Animals↗
PubMed1997

Enhancement of DNA synthetic activity of thymic lymphocytes by the culture supernatant of thymus epithelial cells stimulated by growth hormone.

The authors examined the effect of the culture supernatant of growth hormone (GH)-stimulated thymus epithelial cells (TECs) on DNA synthetic activity of thymic lymphocytes (TLs) and then examined TL proliferation-inducing factors released from the TECs. TEC line, IT-45R1 derived from Wistar strain rat, was used. It was revealed that the supernatant from TECs treated with GH enhanced significantly DNA synthetic activity of TLs and that the activity of the least dense subset of TLs, containing undifferentiated lymphoid cells and the most immature TLs, was significantly increased by the supernatant as compared with other subsets. Anti-insulin like growth factor-I (IGF-I) monoclonal antibody (MAb) binding specifically to C region of IGF-I molecule was added to the culture supernatant from the GH-treated TECs, and then the supernatant was treated with ultrafiltration (MW cutting off; more than 50 kDa). When TLs were incubated with the ultrafiltered supernatant, the enhancement of TL proliferation induced by the supernatant of GH-treated TECs was significantly suppressed. However, the suppression did not descend to the level of TL-proliferative response observed in the supernatant of GH non-stimulated TECs. These results suggested that IGF-I released into the supernatant from GH-stimulated TECs enhances markedly the DNA synthetic activity of TLs and that the TL-proliferation-inducing factors (PIFs) other than IGF-I possibly exist in the supernatant of GH-stimulated TECs.

Animals↗
PubMed1997

Enhancement of thymic lymphocyte proliferation by the culture supernatant of thymus epithelial cells stimulated by prolactin.

Culture supernatant of thymus epithelial cells (TECs) stimulated by prolactin (PRL) enhanced markedly DNA synthetic activity of thymic lymphocytes (TLs) as compared with the hormone-non-stimulated TECs. The supernatant, which was treated with anti-insulin-like growth factor-I (IGF-I) monoclonal antibody (MAb) (binding specifically to C region of IGF-I) has still the capacity of enhancing remarkably TL-proliferation. However, further treatment by ultrafiltration of the MAb-treated supernatant, removing the immune complex (IGF-I and anti-IGF-I MAb) from the supernatant, suppressed significantly the enhanced proliferation of TLs. It is assumed that PRL, like growth hormone (GH), promotes the release of IGF-I from TECs which induces a marked TL-proliferation. Moreover, it seems that the active site for inducing the proliferation is a region different from C, possibly the A or the B regions. TLs, present at different maturation steps, were separated into three subsets by discontinuous density gradient centrifugation and then treated with the supernatant of PRL-stimulated TECs. The least dense subset containing precursor T-cells and the most immature TLs showed the highest proliferative response to the supernatant in the comparison with other subsets and whole TLs. It is possible that the target cells to one of TL-proliferation-inducing factors (PIFs), namely IGF-I, in the supernatant exist in a greater concentration in the most immature step of TL population.

Animals↗
PubMed1997

[Changes of concentrations of umbilical blood monoamines in low birth weight infant and their clinical significance].

OBJECTIVE: To investigate the changes of concentrations of umbilical blood monoamines in low birth weight (LBW) infants and their clinical significance. METHODS: By fluorescence spectrophotometry, the concentrations of umbilical plasma norepinephrine (NE), dopamine (DA), 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in 18 LBW before and after delivery were measured and compared with 20 normal birth weight (NBW) infants. RESULTS: The concentration of all monoamines, especially of the 2 catecholamines, i.e. NE and DA, were markedly lower in LBW than that in NBW (P < 0.05-0.01), regardless of prepartus or postpartus; the concentrations of all monoamines in postpartal umbilical plasma in both of LBW and NBW were higher than those in prepartal, and the increase of NE in NBW showed significant difference (P < 0.05). CONCLUSIONS: The decrease of all monoamines, especially of catecholamines in LBW could be one of the reasons causing the increase of mortality and the decrease of mental and physical development in LBW.

Dopamine↗
PubMed1997

[Studies on teratogenic effects of aluminum on intra uterine fetal development in mice].

Effects of oral administration of different doses of aluminum during pregnancy on intra uterine fetal development in mice were studied with experimental teratological methods. Results showed that over-intake of aluminum could lead obvious teratogenic and toxic effects on fetal development in mice. It could cause formation of encephalocele and dysostosis, intra uterine fetal growth retardation, and increase of embryo death rate, with a obvious dose-dependent relation. It suggests that excessive ingestion of aluminum may be one of the risk factors contributing to congenital neural tube defects, intra uterine fetal growth retardation and perinatal deaths.

Aluminum↗
PubMed1996

Separation of enantiomers of drugs by capillary electrophoresis. III. Beta-cyclodextrin as chiral solvating agent.

Enantiomer separation by capillary zone electrophoresis was studied for a set of 34 chiral drugs. Keeping the concentration of beta-cyclodextrin as a chiral solvating agent as constant as possible led to the separation of seven enantiomeric pairs. Carvedilol, Tetryzoline, Tropicamide and Zopiclone gave a baseline separation, Chlorphenamine, Ketamine, and Orciprenaline a partial separation. Statistical analysis revealed that the best separation factors were observed for a medium degree of interaction with the cyclodextrin. A theory explaining this effect provides a helpful guideline for further optimization.

Azabicyclo Compounds↗
PubMed1996

Karyotype conversion in two patients with chronic myeloid leukaemia after busulphan-induced marrow hypoplasia.

SUMMARY: We report two patients with chronic myeloid leukaemia (CML) developing hypoplasia and karyotype conversion after conventional busulphan therapy. Initially, the percentage of Ph-positive metaphases in marrow for both patients was 100%, which steadily diminished up to a complete disappearance in case 1 and decreased dramatically in case 2 following hypoplasia. Thereafter Southern blot and RT-PCR assays revealed no abnormalities. Both patients have survived 9 years and remained in good clinical and haematological remission without any treatment until recently. We believe that the high sensitivity to busulphan therapy result in hypoplasia and karyotype conversion, which contributed to prolonged survival.

Adult↗