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Biomedical subjects

S Yu

Publications and source records attributed to S Yu.

At least 181 records · Page 10Linked to original sources
PubMed1999

Selective expression of folate receptor beta and its possible role in methotrexate transport in synovial macrophages from patients with rheumatoid arthritis.

OBJECTIVE: To investigate the expression of folate receptors (FR) and reduced folate carrier (RFC) and determine their relevance to methotrexate (MTX) transport in synovial mononuclear cells (SMC) from patients with rheumatoid arthritis (RA). METHODS: Levels of FR and RFC messenger RNA (mRNA) were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) in SMC from RA patients and peripheral blood mononuclear cells from healthy donors. Expression of FR-beta mRNA and protein was determined by Northern blot and Western blot analyses in RA SMC and monocyte/macrophage-lineage cells. FR-beta expression and folic acid binding capacity on the cell surface were examined by flow cytometric analysis and 3H-folic acid binding analysis. Studies of the inhibition of 3H-MTX uptake in the presence of unlabeled folic acid were performed to investigate the uptake of MTX through FR in RA SMC. RESULTS: RT-PCR, Northern blot, and Western blot analyses showed that FR-beta mRNA and protein were expressed selectively in activated monocytes and CD14+ RA SMC. These cells exhibited folic acid binding capacity. Furthermore, the FR-beta protein was shown to have folic acid binding capacity. Uptake of 3H-MTX through RA SMC was significantly inhibited in the presence of unlabeled folic acid. CONCLUSION: These results demonstrate that FR-beta expression is selectively elevated in RA synovial macrophages and suggest that MTX is transported through FR-beta in RA synovial macrophages. The findings suggest that folate antagonists with higher affinity for FR-beta would be useful in the treatment of RA.

Arthritis, Rheumatoid↗
PubMed1999

Cigarette smoking among medical college students in Wuhan, People's Republic of China.

BACKGROUND: This study examined cigarette smoking among a sample of medical college students in Wuhan, People's Republic of China. Specific cultural factors associated with cigarette smoking in China were discussed and issues which need to be studied in the future are presented. METHODS: A self-administrated questionnaire was administered to a sample of 1,611 medical students in 1995. Smoking status was based on self-reported use of cigarettes within the preceding 180 days. Information about demographic characteristics, home residence, annual family income, and smoking status of family members was also obtained. RESULTS: A total of 1,540 (1,201 males and 339 females) completed and returned the questionnaires (response rate 95.6%). None of the 339 female students surveyed reported cigarette smoking. A total of 37.7% (95% confidence interval (CI) = 35.0-40.5%) of the male medical students were current smokers, and 5. 3% (95% CI = 4.0-6.6%) were former smokers. The mean age of beginning to smoke was 16.5 years (95% CI = 8.7-24.3 years). The major reasons for first smoking were stress (42.8%, 95% CI = 38.2-47. 4%), curiosity (34.4%, 95% CI = 29.6-38.4%), and loneliness (33.7%, 95% CI = 28.7-37.4%). Multivariate analyses suggested that age, college year, and having a family member who smoked were significantly associated with cigarette smoking. CONCLUSIONS: The results indicated a need to provide comprehensive tobacco use prevention programs among medical students.

Adolescent↗
PubMed1999

Endothelial function and carotid artery wall thickening in patients with early essential hypertension.

To investigate the relationship between endothelial function and carotid artery wall thickening in patients with early mild essential hypertension, the percent dilatation of humerus diameter and intimal-medial thickening (IMT) of common carotid artery was measured by using high-resolution ultrasound in 20 patients with early mild essential hypertension and 18 patients with normotension. The patients with hypertension had not been treated and their history of increased blood pressure was less than 12 months. In essential hypertension group, the percent dilatation of humerus diameter decreased significantly (2.65 +/- 0.98% vs 6.38 +/- 1.61%); IMT of carotid artery increased (0.88 +/- 0.16 mm vs 0.58 +/- 0.08). There was significant negative correlation between IMT and the percent dilatation of humerus diameter (gamma = -0.82, P < 0.05), and no correlation between IMT and 24 h mean systolic, diastolic pressure (gamma = 0.12 and gamma = 0.07, respectively; P > 0.05). Our results suggested that there was endothelial dysfunction in early mild essential hypertension. Endothelial dysfunction may not only contribute to the pathogenesis of hypertension but also serve as the most important inducing factor leading transformation from hypertension to atherosclerosis.

Atherosclerosis↗
PubMed1999

Phospholipase D as an effector for ADP-ribosylation factor in the regulation of vesicular traffic.

A mammalian phospholipase D (PLD) activity that is stimulated by ADP-ribosylation factor (ARF) has been identified in Golgi-enriched membrane fractions. This activity is due to the PLD1 isoform and evidence from several laboratories indicates that PLD1 is important for the polymerization of vesicle coat proteins on membranes. When expressed in Chinese hamster ovary cells, PLD1 localized to dispersed small vesicles that overlapped with the location of the ERGIC53 protein, a marker for the endoplasmic reticulum (ER)-Golgi intermediate compartment. Cells having increased PLD1 expression had accelerated anterograde and retrograde transport between the ER and Golgi. Membranes from cells having elevated PLD1 activity bound more COPI, ARF, and ARF-GTPase activating protein. These membranes also produced more COPI vesicles than did membranes from control cells. It is likely that PLD1 participates in both positive and negative feedback regulation of the formation of COPI vesicles and is important for controlling the rate of this process.

ADP-Ribosylation Factors↗
PubMed1999

3-(1',1'-Dimethylbutyl)-1-deoxy-delta8-THC and related compounds: synthesis of selective ligands for the CB2 receptor.

The synthesis and pharmacology of 15 1-deoxy-delta8-THC analogues, several of which have high affinity for the CB2 receptor, are described. The deoxy cannabinoids include 1-deoxy-11-hydroxy-delta8-THC (5), 1-deoxy-delta8-THC (6), 1-deoxy-3-butyl-delta8-THC (7), 1-deoxy-3-hexyl-delta8-THC (8) and a series of 3-(1',1'-dimethylalkyl)-1-deoxy-delta8-THC analogues (2, n = 0-4, 6, 7, where n = the number of carbon atoms in the side chain-2). Three derivatives (17-19) of deoxynabilone (16) were also prepared. The affinities of each compound for the CB1 and CB2 receptors were determined employing previously described procedures. Five of the 3-(1',1'-dimethylalkyl)-1-deoxy-delta8-THC analogues (2, n = 1-5) have high affinity (Ki = < 20 nM) for the CB2 receptor. Four of them (2, n = 1-4) also have little affinity for the CB1 receptor (Ki = > 295 nM). 3-(1',1'-Dimethylbutyl)-1-deoxy-delta8-THC (2, n = 2) has very high affinity for the CB2 receptor (Ki = 3.4 +/- 1.0 nM) and little affinity for the CB1 receptor (Ki = 677 +/- 132 nM).

Animals↗
PubMed1999

The Role of Genomic Imprinting of Galpha in the Pathogenesis of Albright Hereditary Osteodystrophy.

Albright hereditary osteodystrophy (AHO) is caused by heterozygous inactivating mutations of the gene encoding the alpha-subunit of the G protein Gs. The Gsalpha gene is a complex gene that uses various alternative promoters and produces various protein products. Recently, it has been shown that this gene is imprinted in a tissue-specific manner. The role of tissue-specific imprinting of Gsalpha in the pathogenesis of AHO is discussed.

Journal Article↗
PubMed1999

Structural and genetic studies of the proliferation disrupter genes of Drosophila simulans and D. melanogaster.

To examine whether structural and functional differences exist in the proliferation disrupter (prod) genes between Drosophila simulans and D. melanogaster, we analyzed and compared both genes. The exon-intron structure of the prod genes was found to be the same--three exons were interrupted by two introns, although a previous report suggested that only one intron existed in D. melanogaster. The prod genes of D. simulans and D. melanogaster both turn out to encode 346 amino acids, not 301 as previously reported for D. melanogaster. The numbers of nucleotide substitutions in the prod genes was 0.0747 +/- 0.0180 per synonymous site and 0.0116 +/- 0.0039 per replacement site, both comparable to those previously known for homologous genes between D. simulans and D. melanogaster. Genetic analysis demonstrated that D. simulans PROD can compensate for a deficiency of D. melanogaster PROD in hybrids. The PRODs of D. simulans and D. melanogaster presumably share the same function and a conserved working mechanism. The prod gene showed no significant interaction with the lethality of the male hybrid between these species.

Amino Acid Sequence↗
PubMed1999

A group of alpha-1,4-glucan lyase genes from the fungi Morchella costata, M. vulgaris and Peziza ostracoderma. Cloning, complete sequencing and heterologous expression.

We here report genes encoding a newly discovered class of starch- and glycogen-degrading enzyme, alpha-1,4-glucan lyase (EC 4.2.2.13), which degrades starch and glycogen to 1,5-anhydro-D-fructose. Two lyases were purified and partially sequenced from the macrofungi Morchella costata and M. vulgaris. The obtained lyase amino acid sequences were used to generate PCR primers, which were further used to probe the fungal genomic libraries. Two lyase genes (Agll1;Mo.cos and Agll1;Mo.vul) from the two fungi were fully sequenced and found to contain a coding region of 3201 bp and 3213 bp, respectively. A total of 13 small introns were found in each of the two genes with identical positions. The two lyase genes share 86% identity at the amino acid level. They encode mature lyases with 1066 and 1070 amino acids, respectively. The deduced molecular masses of 121,530 and 121,971 Da agree with the values found for the two purified lyases. A structure analysis of the promoter regions of the lyase genes revealed a number of putative regulatory DNA elements, such as the AREA and CREA sites, which are related to nitrogen and carbon metabolism, respectively, and the CCAAT/CAAT boxes, which are related to basal expression of genes. A third lyase gene (Agll1;Pe.ost) from the fungus Peziza ostracoderma was partially sequenced to 557 bp. The amino acid sequence deduced from this nucleotide fragment shares 76% identity with the M. costata lyase. Heterologous expression of the M. costata lyase gene was achieved intracellularly in Pichia pastoris and Aspergillus niger.

Amino Acid Sequence↗
PubMed1999

Chloride requirement of kittens for growth is less than current recommendations.

The minimal chlorine (chloride) requirement of kittens for growth was determined in a study in which kittens were given purified diets containing 0.1, 0.4, 0.7, 1.0 or 1.3 g of chloride (Cl) as KCl/kg diet. Each dietary group contained six (three males and three females) specific-pathogen-free kittens; the diets were fed for 30 d. Kittens receiving diets with <0.7 g Cl/kg became alkalotic as evidenced by an increase in blood pH, blood bicarbonate, standard bicarbonate, actual base excess, standard base excess, partial pressure of carbon dioxide (pCO(2)) and total CO(2). In addition, kittens were hypochloremic and hypokalemic; they had decreased serum ionized calcium and a negative chloride balance. On the basis of the chloride balance measurements, a broken-line nonlinear least-square analysis predicted a Cl requirement as 0.89 g Cl/kg diet (22 kJ/g diet). Because the dietary Cl concentration closest to 0.89 g/kg that we tested was 1.0 g Cl/kg, we recommend a minimum chloride requirement of 1.0 g Cl/kg diet for growing kittens. This value is considerably less than the recommended chloride requirement of the National Research Council of 1.9 g Cl/kg diet, or the allowance of the Association of American Feed Control Officials of 3.0 g Cl/kg diet. Because the bioavailability of chloride is high, the previous estimates appear excessive.

Analysis of Variance↗
PubMed1999

Sodium requirement of adult cats for maintenance based on plasma aldosterone concentration.

The sodium requirement of adult cats for maintenance was determined using a randomized block design of eight dietary sodium treatments (0.1, 0.4, 0.5, 0.66, 0.8, 1.2, 1.6 or 2.0 g Na/kg in a casein-lactalbumin-based purified diet) administered for periods of 4 wk. A total of 35 adult specific-pathogen-free domestic shorthaired cats (26 males and 9 females, 1.5-3 y of age) was given an equilibration diet (2 g Na/kg) for 14 d before assignment (or reassignment) to the treatments. A total of 12 cats (8 males, 4 females) was randomly assigned to the lowest six levels of sodium, and four cats to the highest two sodium levels. Cats consuming the diet containing 0.1 g Na/kg had significantly elevated aldosterone concentration in plasma, and packed cell volume. In addition, these cats exhibited anorexia, body weight loss, reduced urinary specific gravity and sodium excretion, and had a negative sodium balance. However, adult cats did not develop polydypsia and polyuria reported in sodium-deficient kittens. Cats given the diet containing 0.66 g Na/kg did not have an increased packed cell volume, but aldosterone concentration in the plasma was significantly elevated. However, cats given diets containing >/=0.8 g Na/kg had plasma aldosterone concentrations </=0.7 nmol/L (reference value for sodium-replete cats) and normal packed-cell volumes. A minimal sodium requirement of adult cats for maintenance of 0.8 g Na/kg diet (energy density = 22 kJ/g diet) or 0.4 mmol Na. kg body weight-1. d-1 is proposed.

Aldosterone↗
PubMed1999

Complete sequence and genome properties of Chinese wheat mosaic virus, a new furovirus from China.

The complete nucleotide sequence of a virus infecting winter wheat in Shandong province, China has been determined. This was previously thought to be soil-borne wheat mosaic virus but, while the two viruses are related, they are only 75% (RNA1) and 63% (RNA2) identical at the nucleotide level, while the amino acid sequences share from 62% (19 kDa RNA2 product) to 84% (RNA1 replicase) identity. The analysis shows that the Chinese virus should be considered a new member of the genus Furovirus and has been named Chinese wheat mosaic virus (CWMV). A Cys-Gly ... Cys-Gly-X-X-His amino acid pattern was identified in the cysteine-rich protein of CWMV and those of several other plant virus genera, which seems likely to have some functional significance.

Amino Acid Sequence↗
PubMed1999

Transcriptional control of the iron-responsive fxbA gene by the mycobacterial regulator IdeR.

Exochelin is the primary extracellular siderophore of Mycobacterium smegmatis, and the iron-regulated fxbA gene encodes a putative formyltransferase, an essential enzyme in the exochelin biosynthetic pathway (E. H. Fiss, Y. Yu, and W. R. Jacobs, Jr., Mol. Microbiol. 14:557-569, 1994). We investigated the regulation of fxbA by the mycobacterial IdeR, a homolog of the Corynebacterium diphtheriae iron regulator DtxR (M. P. Schmitt, M. Predich, L. Doukhan, I. Smith, and R. K. Holmes, Infect. Immun. 63:4284-4289, 1995). Gel mobility shift experiments showed that IdeR binds to the fxbA regulatory region in the presence of divalent metals. DNase I footprinting assays indicated that IdeR binding protects a 28-bp region containing a palindromic sequence of the fxbA promoter that was identified in primer extension assays. fxbA regulation was measured in M. smegmatis wild-type and ideR mutant strains containing fxbA promoter-lacZ fusions. These experiments confirmed that fxbA expression is negatively regulated by iron and showed that inactivation of ideR results in iron-independent expression of fxbA. However, the levels of its expression in the ideR mutant were approximately 50% lower than those in the wild-type strain under iron limitation, indicating an undefined positive role of IdeR in the regulation of fxbA.

Bacterial Proteins↗
PubMed1999

Isolation of Helicobacter canis from a colony of bengal cats with endemic diarrhea.

On the basis of biochemical, phenotypic, and 16S rRNA analyses, Helicobacter canis was isolated from Bengal cats with and without chronic diarrhea. Because the cats were coinfected with other potential pathogens, including Campylobacter helveticus, and because H. canis was isolated from nondiarrheic cats, the causal role of H. canis in producing the diarrhea could not be proven. Histologically, the colons of the four affected cats were characterized by mild to moderate neutrophilic, plasmacytic, and histocytic infiltrates in the lamina propria. Rare crypt abscesses were also noted for three cats but were a more prominent feature of the colonic lesions noted for the fourth cat. This is the first observation of H. canis in cats and raises the possibility that H. canis, like H. hepaticus and H. bilis in mice, can cause inflammation of the colon, particularly in hosts with immune dysregulation. Further studies are needed to determine the importance of H. canis as a primary enteric pathogen in cats and the role of cats in the possible zoonotic spread of H. canis to humans.

Animals↗
PubMed1999

Decreased renal Na-K-2Cl cotransporter abundance in mice with heterozygous disruption of the G(s)alpha gene.

Transport processes along the nephron are regulated in part by hormone stimulation of adenylyl cyclases mediated by the heterotrimeric G protein G(s). To assess the role of this pathway in the regulation of Na-K-2Cl cotransporter abundance in the renal thick ascending limb (TAL), we studied mice with heterozygous disruption of the Gnas gene, which codes for the alpha-subunit of G(s). Outer medullary G(s)alpha protein abundance (as assessed by semiquantitative immunoblotting) and glucagon-stimulated cAMP production were significantly reduced in the heterozygous G(s)alpha knockout mice (GSKO) relative to their wild-type (WT) littermates. Furthermore, Na-K-2Cl cotransporter protein abundance in the outer medulla was significantly reduced (band density, 48% of WT). In addition, GSKO mice had a significantly reduced (72% of WT) urinary osmolality in response to a single injection of 1-deamino-[8-D-arginine]vasopressin (DDAVP), a vasopressin analog. In contrast, outer medullary protein expression of the type 3 Na/H exchanger (NHE-3) or Tamm-Horsfall protein did not differ between the GSKO mice and their WT littermates. However, abundance of type VI adenylyl cyclase was markedly decreased in the outer medullas of GSKO mice, suggesting a novel feed-forward regulatory mechanism. We conclude that expression of the Na-K-2Cl cotransporter of the TAL is dependent on G(s)alpha-mediated hormone stimulation, most likely due to long-term changes in cellular cAMP levels.

Adenylyl Cyclases↗
PubMed1999

Expansion and immunological study of human tumor infiltrating gamma/delta T lymphocytes in vitro.

Goffa/delta T cells have stimulated a lot of interest because of their unique features in antigen recognition and cytotoxicities to many autologous and/or allogeneic tumor cells. We have developed a novel method to selectively expand larger amounts of human tumor-infiltrating gamma/delta T lymphocytes (gamma/delta TILs) ex vivo by immobilized pan- anti-TCRgamma/delta monoclonal antibody in the presence of exogenous IL-2. The expanded gamma/delta TILs mainly expressed CD45RO and HLA-DR molecules and did not express CD4. CD8+ gamma/delta TILs accounted for 19% of gamma/delta TILs. The expression of CD25 molecule on expanded gamma/delta T cells was inducible and downregulated following a time course. The Vdelta1 and Vdelta2 subsets amount to 37 and 58%, respectively. The expanded gamma/delta TILs show an IL-2-dependent proliferation, MHC class I-unrestricted and TCRgamma/delta-related cytotoxicities to two MHC class I+ and two MHC class I+ allogeneic tumor cell lines in vitro.

Adenocarcinoma↗
PubMed1999

Identification of two novel deletion mutations within the Gs alpha gene (GNAS1) in Albright hereditary osteodystrophy.

Albright hereditary osteodystrophy (AHO) is a genetic disorder characterized by short stature, skeletal defects, and obesity. Within AHO kindreds, some affected family members have only the somatic features of AHO [pseudopseudohypoparathyroidism (PPHP)], whereas others have these features in association with resistance to multiple hormones that stimulate adenylyl cyclase within their target tissues [pseudohypoparathyroidism type Ia (PHP Ia)]. Affected members of most AHO kindreds (both those with PPHP and those with PHP Ia) have a partial deficiency of Gs alpha, the alpha-subunit of the G protein that couples receptors to adenylyl cyclase stimulation, and in a number of cases heterozygous loss of function mutations within the Gs alpha gene (GNAS1) have been identified. Using PCR with the attachment of a high melting domain (GC-clamp) and temperature gradient gel electrophoresis, two novel heterozygous frameshift mutations within GNAS1 were found in two AHO kindreds. In one kindred all affected members (both PHP Ia and PPHP) had a heterozygous 2-bp deletion in exon 8, whereas in the second kindred a heterozygous 2-bp deletion in exon 4 was identified in all affected members examined. In both cases the frameshift encoded a premature termination codon several codons downstream of the deletion. In the latter kindred affected members were previously shown to have decreased levels of GNAS1 messenger ribonucleic acid expression. These results further underscore the genetic heterogeneity of AHO and provides further evidence that PHP Ia and PPHP are two clinical presentations of a common genetic defect. Serial measurements of thyroid function in members of kindred 1 indicate that TSH resistance progresses with age and becomes more evident after the first year of life.

Amino Acid Sequence↗
PubMed1999

Antibodies to a microbial peptide sharing sequence homology with betaA3-crystallin damage lens epithelial cells in vitro and in vivo.

Circulating auto-antibodies (Abs) against lens antigens (Ags) are highly prevalent in patients with cataract, but their origin and pathogenic significance are unknown. We hypothesized that Abs raised after exposure to infectious microbes could cross-react with lens Ags. To test this hypothesis, we generated a monoclonal Ab to human betaA3-crystallin. Epitope analysis indicated that the ETQAE sequence in the N-terminus region of betaA3-crystallin was critical for mounting a humoral response. Similar sequences were found in three microbial Ags. Mice injected with a microbial oligopeptide containing ETQAE emulsified with complete Freund's adjuvant (CFA) raised Abs which cross-reacted with betaA3-crystallin and developed lens epithelial cell (LEC) damage in vitro. We also genetically engineered an betaA3-crystallin-expressing E. coli. Mice immunized with the recombinant E. coli developed LEC damage. These results support the hypothesis that exposure to microbes having Ags homologous to self Ags can trigger a humoral immune response that leads to LEC damage in mice.

Amino Acid Sequence↗