Biomedical subjects

L Jin

Publications and source records attributed to L Jin.

At least 289 records · Page 16Linked to original sources

PubMed1997

Structure of the collagen-binding domain from a Staphylococcus aureus adhesin.

The crystal structure of the recombinant 19,000 M(r) binding domain from the Staphylococcus aureus collagen adhesin has been determined at 2 A resolution. The domain fold is a jelly-roll, composed of two antiparallel beta-sheets and two short alpha-helices. Triple-helical collagen model probes were used in a systematic docking search to identify the collagen-binding site. A groove on beta-sheet I exhibited the best surface complementarity to the collagen probes. This site partially overlaps with the peptide sequence previously shown to be critical for collagen binding. Recombinant proteins containing single amino acid mutations designed to disrupt the surface of the putative binding site exhibited significantly lower affinities for collagen. Here we present a structural perspective for the mode of collagen binding by a bacterial surface protein.

Adhesins, Bacterial↗

PubMed1997

Long-term expression of Fos-related antigen and transient expression of delta FosB associated with seizures in the rat hippocampus and striatum.

Systemic administration of kainic acid (KA), an analogue of glutamic acid, causes limbic seizures and pathophysiological changes in adult rats that are very similar to human temporal lobe epilepsy. One of the earliest changes in gene expression after treatment with KA is the induction of immediate-early genes. The fos and jun families are frequently studied immediate-early genes that are induced by KA. Several groups, including ours, have recently reported that a 35-kDa Fos-related antigen (FRA) is induced for a protracted time by various stimuli. It has been suggested that this FRA is delta FosB, which has a molecular mass of approximately 35 kDa. The present study characterizes the long-term expression of FRA and delta FosB after systemic treatment with KA. Immunocytochemistry and western blot analysis using an antibody that cross-reacts with all known FRAs showed that a 35-kDa FRA was induced at high levels in both the hippocampus and striatum for up to 1 month by KA. A semiquantitative PCR analysis showed that delta FosB was induced by KA, but its expression lasted for only 6 h. This result was also verified by northern blot analysis. These results suggested that the 35-kDa FRA with long-term elevated levels seen with western blot analysis and immunocytochemistry is a new species of the FRA and not delta FosB. The long-term expression of FRA in both the hippocampus and striatum may be associated with the pathophysiological changes after KA administration.

Animals↗

PubMed1997

Estrogen receptor expression and growth-promoting function in human choriocarcinoma cells.

Tamoxifen (1.0 microM) was found to inhibit the expression of a thymidine kinase (TK) promoter-reporter gene, lacking an estrogen response element (ERE), in transiently transfected BeWo cells, suggesting that inhibition of TK promoter activity was linked to secondary estrogen-dependent effects on BeWo cell function. Estradiol (0.05-0.45 microM) stimulated BeWo cell proliferation and increased the percentage of S-phase cells. Tamoxifen (1.35-4.05 microM) inhibited BeWo cell growth and antagonized the stimulatory actions of 0.15 microM estradiol. Reverse transcription-polymerase chain reaction and Western analyses confirmed the presence of estrogen receptor (ER) transcripts and the 67-kD ER in BeWo cells. The BeWo cell ER binds to an ERE consensus sequence and the ER-ERE complex is supershifted by antibodies directed against the ER. We conclude that BeWo cells express a functional ER that is important for the control of BeWo cell proliferation, suggesting a potential role for estrogens in mediating placental trophoblast growth and development.

Animals↗

PubMed1997

The diversity of measles virus in the United Kingdom, 1992-1995.

Three distinct genotypes were identified amongst 50 measles virus (MV) strains characterized in the UK between 1992 and 1995 by direct sequencing of the RT-PCR products amplified from clinical specimens. All three genotypes were related to viruses previously reported in the United States or in continental Europe. Phylogenetic analyses of 255 and 152 nucleotide sequences from the N and M genes, respectively, generated very similar lineages. The degree of divergence between genotypes was 3.5-16% and 2.6-7.9% in the N and the M genes, respectively. MV genotypes which circulated during the 1970s and 1980s in the UK were not detected in this period. Comparison of the C-terminal regions of the N gene sequences of UK strains isolated or detected between 1974 and 1995 suggests that there have been multiple genotypes of MV circulating in the UK over the past 20 years.

Base Sequence↗

PubMed1997

Detection of numerous Y chromosome biallelic polymorphisms by denaturing high-performance liquid chromatography.

Y chromosome haplotypes are particularly useful in deciphering human evolutionary history because they accentuate the effects of drift, migration, and range expansion. Significant acceleration of Y biallelic marker discovery and subsequent typing involving heteroduplex detection has been achieved by implementing an innovative and cost-efficient method called denaturing high-performance liquid chromatography (DHPLC). The power of the method resides in its sensitivity and ability to rapidly compare amplified sequences in an automated manner. We have determined the allelic states of 22 Y polymorphisms; 19 of which are unreported, in 718 diverse extant chromosomes; established haplotype frequencies; and deduced a phylogeny. All major geographic regions, including Eurasia, are characterized by mutations reflecting episodes of genetic drift and expansion. Most biallelic markers are localized regionally. However, some show wider dispersal and designate older, core haplotypes. One transversion defines a major haplogroup that distinguishes a previously unknown deep, apparently non-African branch. It provides evidence of an ancient bottleneck event. It is now possible to anticipate the inevitable detailed reconstruction of human Y chromosome genealogy based on several tens to even hundreds of these important polymorphisms.

Alleles↗

PubMed1997

Microsatellite data support an early population expansion in Africa.

We have developed a method for the analysis of microsatellite data that is useful in the elucidation of the demographic history of populations. This method, the PK distribution method of pairwise comparisons, is analogous to the mismatch distribution of sequence comparisons developed for the analysis of mitochondrial sequence data by Rodgers and Harpending and is defined as the distribution of the number of repeat unit differences between alleles when each allele in a sample is compared with every other allele in the sample. Using computer simulations of microsatellite loci, we show that the shape of the distribution of PK changes in a distinctive manner as a function either of time since population expansion or effective population size. Increases in both of these affect the PK distribution in a similar fashion leading to a change from a steep distribution with a Po peak to one with a nonzero peak. Analysis of three data sets from surveys of microsatellite loci in ethnographically defined populations reveals that most (9/12) of the African populations analyzed, but none of the 30 non-African populations showed PK distributions with nonzero peaks. These PK distributions indicate either an earlier expansion or a larger effective population size for African populations. This observation is consistent with the hypothesized African origin of modern human.

Africa↗

PubMed1997

The complex mutation pattern of a microsatellite.

DQCAR is a (CA)n microsatellite located in the HLA class II region and tightly linked to HLA-DQB1. Previous studies showed a strikingly low level of size variation in DQCAR alleles within an extensive subfamily of HLA-DQ subtypes (DQ1). DQCAR alleles in non-DQ1 subtypes showed a higher degree of size polymorphism. In this study sequence analysis demonstrates that DQ1-associated DQCAR alleles have a single C-->A nucleotide substitution interrupting the CA repeat array. Frequent CA-->GA mutations are also observed in DQ1-associated microsatellites with identical allele sizes. In contrast, DQCAR alleles associated with non-DQ1 haplotypes display a perfect CA repeat sequence and the variation in allele size is attributable only to differences in the number of CA repeats. Our results imply that several mutational mechanisms are involved in the generation of allelic diversity within the same microsatellite locus. The possibility of different mutation rates in the same locus should to be taken into account when using these markers in evolutionary and disease studies.

Alleles↗

PubMed1997

DQ microsatellite association studies in three ethnic groups.

Polymorphism at the level of three microsatellite markers (DQCAR, DQCARII, G51152) located in the HLA-DQ region was characterized in 78 10th International Histocompatibility Workshop B-cell lines, 718 random Japanese Asians, 99 Norwegian Caucasians and 95 New Guinean Aborigines with established HLA-DRB1, -DQA1 and -DQB1 typing. DQCAR, DQCARII, and G51152 result in 13, 13, and 11 alleles respectively. All three markers were in tight linkage disequilibrium with HLA-DRB1, -DQA1 and -DQB1. DRB1, DQA1, DQCARII, DQCAR, DQB1, and G51152 haplotypes could be defined for all subjects. In fact, DQ microsatellite typing data could predict DQA1 and DQB1 genotypes with high accuracy and may be used as a simple first pass HLA-DQ typing method. The haplotype data was also used to determine recombination in the DRB1-DQA1 (about 80 kb), DQA1-DQCARII (about 4.5 kb), DQCARII-DQCAR (about 7.5 kb), DQCAR-DQB1 (about 1-1.5 kb) and DQB1-G51152 (about 20-25 kb) genomic segments and the relative rate of slippage microsatellite mutations for DQCAR, DQCARII, and G51152. This led us to conclude that recombination is more frequent in the DRB1-DQA1 and DQCAR-DQCARII segments, thus suggesting cross-overs within small genomic segments are not proportional to genetic distance. We also observed that DQCAR had a higher mutation rate than DQCARII or G51152 and that 1 or 2 CA slippage mutations were arising more frequently from large size microsatellite alleles.

DNA, Satellite↗

PubMed1997

Prolactin receptor messenger ribonucleic acid in normal and neoplastic human pituitary tissues.

We examined the specific cell types in normal human pituitaries that expressed PRL receptor (PRL-R) messenger ribonucleic acid (mRNA) by combined in situ hybridization and immunohistochemistry. The distribution of PRL-R mRNA in 28 pituitary adenomas was examined by in situ hybridization and reverse transcription-PCR in 12 cases of adenomas. In another set of experiments, 34 PRL adenomas from men, women, and bromocriptine-treated patients were analyzed for PRL-R by in situ hybridization. In the normal pituitary, PRL- and LH-producing cells had significantly more mean grain counts per cell and higher percentages of cells positive for PRL-R than GH and TSH cells. PRL-R mRNA was present in all groups of adenomas by in situ hybridization and reverse transcription-PCR. PRL adenomas had a significantly higher density of labeling compared to other adenoma types. Although there was no difference in the levels of PRL-R mRNA in PRL adenomas from men and premenopausal and postmenopausal women, patients treated with bromocriptine before pituitary surgery had significantly lower levels of PRL-R compared to all other groups. These results indicate that in the normal pituitary, PRL and LH cells have the highest level of PRL-R mRNA, whereas PRL adenomas have significantly higher levels of PRL-R mRNA than other types of adenomas, and bromocriptine treatment decreases the levels of PRL-R mRNA in PRL adenomas.

Adenoma↗

PubMed1997

Gonadotropin-releasing hormone and gonadotropin-releasing hormone receptor messenger ribonucleic acids expression in nontumorous and neoplastic pituitaries.

In the nontumorous pituitary, GnRH stimulates the release and synthesis of LH and FSH by gonadotroph cells via the GnRH receptor (GnRH-R). Little is known, however, about expression of GnRH and GnRH-R messenger RNAs (mRNAs) in nontumorous pituitary tissue and in adenomas. To learn more about the distribution and regulatory roles of GnRH and its receptor, we investigated the expression of both GnRH and GnRH-R mRNAs in nontumorous human pituitary and in various types of pituitary adenomas using the RT-PCR, in situ hybridization, and in situ hybridization in combination with RT-PCR (in situ RT-PCR). Using RT-PCR, GnRH mRNA was found to be expressed in normal human pituitaries and in all types of adenomas. Similarly, GnRH-R mRNA was expressed in nontumorous human pituitaries and in most, but not all, adenomas. These included 5 gonadotroph adenomas, 6 null cell adenomas, 1 of 2 GH-producing tumors, and 1 of 2 ACTH-producing adenomas, but not in the 2 PRL-producing adenomas examined. In situ hybridization studies showed GnRH and GnRH-R mRNAs in all 3 nontumorous pituitaries and in 12 of 33 (36.4%) and 10 of 33 adenomas (30.3%), respectively. Using an indirect in situ RT-PCR technique to increase the sensitivity of the in situ localization, GnRH and GnRH-R mRNAs were detected in 29 (87.9%) and 25 (75.8%) of 33 adenomas, respectively. This is the first report of the localization of GnRH and GnRH-R mRNAs in individual pituitary adenoma cells using in situ RT-PCR. The frequent expression of GnRH and GnRH-R mRNAs in pituitary cells suggests that GnRH has autocrine/paracrine functions in nontumorous and neoplastic pituitary tissues.

Gonadotropin-Releasing Hormone↗

PubMed1997

A growth hormone-releasing hormone-producing pancreatic islet cell tumor metastasized to the pituitary is associated with pituitary somatotroph hyperplasia and acromegaly.

The functional and morphological changes in the pituitary gland caused by a GHRH-producing pancreatic islet cell tumor that metastasized to the pituitary and caused somatotroph hyperplasia are described. A 52-yr-old woman presented with loss of visual acuity, diabetes insipidus, and acromegaly caused by a GHRH-producing endocrine carcinoma metastasized to the pituitary. The serum GHRH, GH, and insulin-like growth factor I levels of the patient were elevated. Immunohistochemical and in situ hybridization study revealed GHRH immunoreactivity and GHRH messenger RNA (mRNA) in the metastatic tumor cells. The anterior pituitary showed hyperplasia of somatotroph cells with intact acinar structure that did not contain an adenoma, determined by light microscopy using silver impregnation. Electron microscopy revealed hyperplastic characteristics of densely granulated somatotrophs. In situ hybridization documented strong signals for GH mRNA and pituitary-specific transcriptional factor Pit-1 mRNA in the hyperplastic somatotrophs. A weak signal for GHRH receptor mRNA was detected in these somatotrophs. However, using in situ RT-PCR, GHRH receptor mRNA was more conclusively observed in most of the somatotrophs. The excessive production of GHRH by metastatic tumor may have resulted in somatotroph hyperplasia by the synergistic effects of Pit-1 and GHRH receptor. It can be concluded that the pathogenesis of pituitary adenoma formation is primarily mediated by other factors than hypothalamic hormone.

Acromegaly↗

PubMed1997

Adrenomedullin gene delivery reduces blood pressure in spontaneously hypertensive rats.

Adrenomedullin (ADM) is a potent vasoactive peptide. In this study, we explored the effects of a continuous supply of ADM by somatic gene delivery on spontaneously hypertensive rats (SHR). DNA constructs containing the human ADM cDNA fused to either the cytomegalovirus promoter (CMV-cADM) or Rous Sarcoma virus 3'-long terminal repeat (RSV-cADM) were intravenously injected into SHR through the tail vein. Expression of human ADM in SHR was identified in the kidney, adrenal gland, heart, and lung by radioimmunoassay and reverse transcription-polymerase chain reaction followed by Southern blot analysis. A single injection of ADM plasmid DNA in young adult SHR (7 wk old) caused a significant reduction in systolic blood pressure for up to 5 wk (p < 0.05). A second injection of CMV-cADM 5 wk after the first delivery resulted in a further reduction in blood pressure for another 3 wk (p < 0.001). A maximal blood pressure reduction of 22 mmHg in SHR was observed 7 wk after injection of CMV-cADM plasmid DNA (185 +/- 1.7 mmHg, n = 6, p < 0.001), and a reduction of 15 mmHg was observed after injection of RSV-cADM (192 +/- 2.7 mmHg, n = 6, p < 0.001), as compared with control rats given vector DNA (207 +/- 2.4 mmHg, n = 6). Similarly, injection of CMV-cADM plasmid DNA in adult SHR (10 wk old) resulted in a significant reduction in blood pressure for up to 6 wk. Antibodies to either human ADM or its plasmid DNA were not detected in rat sera after the second injection. These studies indicate that intravenous injection of the human ADM gene in hypertensive rats results in expression of the foreign gene and induces a long-lasting reduction in blood pressure.

Adrenomedullin↗

PubMed1997

[Surgical treatment for advanced gallbladder cancer].

To rise the resection rate and survival rate for advanced gallbladder cancer (GBC), we operated on forty cases of advanced GBC. 34 cases had obstractive jundice, and 8 palpable abdominal mass. Externded radical cholecystectomy was performed in 11 cases of advanced GBC in which the tumor invaded the surrounding organs or tissues but without distantce metastasis. Follow-up showed that the survival period was between 8 and 32 months (average 18.8 months), 1 and 2 years survival rates were 54.4% and 27.3%. Palliative operations were performed in other 29 advanced GBC cases of distant metastasis. All of the cases died within one year. We suggest that extended radical cholecystectomy is effective for advanced GBC.

Adenocarcinoma↗

PubMed1997

[Changes of 5-HT2A receptor binding on platelet of patients with CAD and the effects of exercise test].

It is known both 5-HT2A receptors of platelet and vascular smooth muscle regulate vascular constriction and platelet aggregation to 5-HT challenge. And that 5-HT-induced hypperreactivity of vascular smooth muscle and platelet were noted in patients with coronary artery disease (CAD). In order to investigate the mechanism of platelet hyperreactivity in cardiovascular disease. Platelet 5-HT2A receptor were measured by specific binding of 3H-ketanserin in patients with CAD (CAD group) and patients with chest pain but without CAD as well as healthy subjects (control group) before and after submaximal treadmill exercise. At the same time the levels of plasma 5-HT were also measured. The results showed: (1) In the resting state, 3H-ketanserin exhibited saturable binding with Bmax of 71.1 +/- 10.1 fmol/mg protein, Kd 1.35 +/- 0.20 nmol/L in control group (n = 8) and with Bmax of 102.1 +/- 22.2 fmol/mg protein, Kd 2.44 +/- 0.66 nmol/L in CAD group (n = 10). Between two groups had no significant difference (P > 0.05). And the specific binding of 2.0 nmol/L 3H-ketanserin and the level of plasma 5-HT in CAD group were higher than those in control group (P < 0.05). (2) After exercise all of the specific binding of 2.0 nmol/L 3H-ketanserin, Bmax of receptor binding and the level of plasma 5-HT were significantly increased in CAD group but not in control group. The above results suggested that the up-regulation of platelet 5-HT2A receptor was involved in the platelet hyperreactivity in CAD. The submaximal treadmill exercise had no significant effect on platelet function in control group, but it could lead to platelet 5-HT2A receptor increment and platelet activation in CAD group. Therefore, these changes of platelet might play a role in the acute myocardial ischemia induced by exercise.

Adult↗

PubMed1997

[Development of a SIRI-TOFMS and the application research progress].

The only one set of Sputter Initiated Resonance Ionization-Time of Flight Mass Spectrometer (SIRI-TOFMS) in China was designed and developed. A liquid gallium ion source with micron level diameter of beam, frame-style piezoeletric ceramic sub-micron sample manipulator, a secondary electron imaging system and a computer controlled precise targeting system as well as a real colour big screen image displaying system were added so as to improve its microanalysis capability. By means of this apparatus, trace analysis of Au in minerals and Cu in standard steel samples were carried out. The detection limit of them is 40ng/ and microg/g level, respectively. Aside from the above detections, other preliminary researches ere also performed.

English Abstract↗

PubMed1997

Urinary and tissue levels of scatter factor in transitional cell carcinoma of bladder.

PURPOSE: We previously reported increased titers of scatter factor in urine of 20 patients with transitional cell carcinoma of the bladder compared to noncancer and cancer control groups. Scatter factor was also found in bladder tumor extracts but the number of samples examined was too small for detailed analysis. We report a followup study of larger numbers of patients with transitional cell carcinoma and controls. MATERIALS AND METHODS: The scatter factor content of urine samples and bladder tissue extracts was measured by enzyme-linked immunosorbent assay. Values were normalized per milligram creatinine or tissue protein. Statistical analysis was performed using the Mann-Whitney U test or, for multiple comparisons, the Kruskal-Wallis H test. RESULTS: Patients with transitional cell carcinoma of the bladder (52) had higher urinary scatter factor titers than did 24 normal subjects (p < 0.001) or 14 with benign prostatic hypertrophy (p < 0.001), 49 with prostate cancer (p < 0.001) and 13 with other genitourinary tract cancers (p < 0.01). Transitional cell carcinoma cases with clinicopathological evidence of disease had greater urinary scatter factor levels than those with no evidence of disease at urine sampling (p < 0.01). However, patients with transitional cell carcinomas in remission still had much greater urinary scatter factors than did normal subjects (p < 0.001). In contrast, patients with active prostate cancer had urinary scatter factor levels similar to those in remission. Patients with muscle invasive or high grade transitional cell carcinomas tended to have higher urinary scatter factor levels than patients with nonmuscle invasive or low grade tumors, respectively, but the differences were not significant. Greater levels of scatter factor were present in tissue extracts of muscle invasive transitional cell carcinomas than in nonmuscle invasive tumors (p < 0.001) or nontumor tissue (p < 0.02). Invasion was more closely related to tissue scatter factor content than tumor grade, since high grade noninvasive transitional cell carcinomas had a scatter factor content similar to that of low grade noninvasive transitional cell carcinomas. CONCLUSIONS: These studies suggest that scatter factor may be a marker of bladder cancer, urinary scatter factor titers tend to reflect disease activity and particularly high tissue titers of scatter factor are found in muscle invasive cancers. A larger prospective study will be necessary to determine the clinical significance of elevated scatter factor titers in transitional cell carcinoma of the bladder.

Carcinoma, Transitional Cell↗

PubMed1997

Inhibition of lipopolysaccharide-induced nitric oxide and cytokine production by ultralow concentrations of dynorphins in mixed glia cultures.

Dynorphins (dyn) are a major class of endogenous opioid peptides that modulate the functions of immune cells. However, the effects of dyn on the immune functions of glial cells in the central nervous system (CNS) have not been well characterized. Because nitric oxide (NO) and the proinflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) produced by glial cells are involved in various physiopathological conditions in the CNS, this study examined the effects of dyn on the production of NO and TNF-alpha from mouse glial cells treated with lipopolysaccharide (LPS). LPS induced a concentration-dependent increase in the production of NO or TNF-alpha from the mouse primary mixed glia cultures. Ultralow concentrations (10(-16)-10(-12) M) of dynorphin (dyn) A-(1-8) significantly inhibited the LPS-induced production of NO or TNF-alpha. The inhibitory effects of dyn A-(1-8) were not blocked by nor-binaltorphimine, a selective kappa opioid receptor antagonist. U50-488H, a selective kappa opioid receptor agonist, did not affect the LPS-induced production of NO or TNF-alpha. Ultralow concentrations (10(-16)-10(-12) M) of des-[Tyr1]-dyn A-(2-17), a nonopioid analog that does not bind to kappa opioid receptors, exhibited the same inhibitory effects as dyn A-(1-17) and dyn A-(1-8). These results suggest that dyn modulate the immune functions of microglia and/or astrocytes in the brain and these modulatory effects of dyn are not mediated by classical kappa opioid receptors.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed1997

Heterotopic brain in the pterygopalatine fossa.

Heterotopic brain outside the cranial vault is uncommon. It occurs most frequently in the nasal region, although rests elsewhere in the aerodigestive tract have been reported. We describe a case of heterotopic brain in the pterygopalatine fossa.

Biopsy↗