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Biomedical subjects

H Yu

Publications and source records attributed to H Yu.

At least 91 records · Page 5Linked to original sources
PubMed1996

Assay of prostate-specific antigen from whole blood spotted on filter paper and application to prostate cancer screening.

We report the measure of prostate-specific antigen (PSA) from extracts of blood dried on filter paper. Five 3-mm (diameter) paper discs containing approximately 25 microL of dried whole blood were punched from the filter paper and extracted with 500 microL of buffer. Recovery of PSA was > 92%. Imprecision of the filter paper procedure was <10% when corresponding whole-blood concentrations were >0.35 micrograms/L. PSA recovery was unaffected whether blood was applied to the filter as one 85-microL aliquots, two 43-microL aliquots, or three 28-microL aliquots. PSA is contained in the plasma fraction. Variation in hematocrit from 0.61 to 0.31 caused <+/-10% change in filter paper PSA. Regression analysis showed: filter paper PSA = 0.86 whole-blood PSA - 0.02; Sy/x = 0.44. Men (153) without prostate cancer gave a 95th percentile of 4.8 micrograms /L. PSA in filter paper dried blood was stable for >1 month at -20 to 37 degrees C and showed no loss of recovery after being mailed to a hot climate. We conclude that the filter paper procedure can reliably distinguish normal from increased concentrations of PSA and that it could facilitate screening to detect occult prostate cancer in large-scale mail-in programs to centralized laboratories.

Adult↗
PubMed1996

Ultrasensitive detection of prostate-specific antigen by a time-resolved immunofluorometric assay and the Immulite immunochemiluminescent third-generation assay: potential applications in prostate and breast cancers.

We report an ultrasensitive time-resolved immunofluorometric assay (TRIFA) for prostate-specific antigen (PSA). The assay is an improvement of our previous report (Clin Chem 1993;39:2108-14) and includes the utilization of two monoclonal antibodies and a one-step incubation period, which greatly reduces analysis time. The new method demonstrates a superior lower analytical limit of detection (< or = 1 ng/L), a wide dynamic range, absence of a hook effect at 10(6) ng/L PSA, and equimolarity for free PSA and PSA-antichymotrypsin complex. Also, we have compared several aspects of our TRIFA with a commercially available third-generation assay (Immulite). An evaluation of breast tumor cytosol extracts from 315 patients shows PSA immunoreactivity > 15 ng/g of total protein in 28% and 23% by TRIFA and Immulite analysis, respectively. Both methods demonstrate a significant association between breast tumor PSA immunoreactivity and progesterone and estrogen receptor positivity (P <0.001). Analysis of serum samples obtained for monitoring of postradical prostatectomy patients reveals significant PSA changes at concentrations undetectable by conventional methods. The significance of these results as well as the potential applications of ultrasensitive PSA assays in breast and prostate cancers are discussed.

Breast Neoplasms↗
PubMed1996

Prostaglandin D2 synthase: a component of human amniotic fluid and its association with fetal abnormalities.

Prostaglandin D2 (PGD2) synthase is responsible for PGD2 production in the brain. Western blot analysis of human amniotic fluid and probing with a polyclonal antibody against prostate-specific antigen (PSA) revealed a strong immunoreactive band with a molecular mass of 25 kDa. The immunoreactive species, which does not react with monoclonal anti-PSA antibodies, was purified to homogeneity from 1 L of amniotic fluid through successive cycles of gel filtration and ion-exchange chromatography. Amino acid sequence analysis (15 cycles) revealed that the protein was highly homologous or identical to PGD2 synthase. On semiquantitative analysis, PGD2 synthase concentration appears to increase dramatically during gestational weeks 12-25 and then declines slowly until term. PGD2 synthase concentration in amniotic fluid was altered in many abnormal pregnancies, most notably its decrease in trisomic fetuses and fetuses with renal abnormalities.

Amino Acid Sequence↗
PubMed1996

Links between hypertension and myocardial infarction.

The mechanisms through which hypertension contributes to the occurrence of myocardial infarction should be discussed from two points of view: (1) common risk factors for the two diseases, such as genetic risk, insulin resistance, sympathetic hyperactivity, and vasoactive substances such as angiotensin K, and (2) linking factors that are induced by hypertension and contribute to the development of atherosclerosis and myocardial infarction, such as atherosclerosis and left ventricular hypertrophy. Mechanical stress on blood vessels because of high blood pressure is an especially important factor in endothelial dysfunction, the progression of atherosclerosis, and plaque rupture. This article concentrates on these factors from the perspective of their relationship with the renin-angiotensin system, because recent multicenter trials have demonstrated that angiotensin-converting enzyme inhibitors are effective for preventing recurrence of myocardial infarction.

Arteriosclerosis↗
PubMed1996

[A comparison of plasma amino acid concentrations between appropriate and small for gestational age fetuses].

OBJECTIVE: To investigate the role of amino acid played in pathogenesis of small for gestational age (SGA) fetuses. METHODS: Plasma amino acids' concentrations (PAAC) of umbilical venous samples obtained by cordocentesis before labor or at cesarean section were measured in 30 cases of appropriate for gestational age (AGA) fetuses at different gestational age. PAAC of both mother and fetuses were measured and compared in 10 cases of SGA and 10 cases of AGA. RESULTS: In cases of AGA, the PAAC in fetuses (3.11 +/- 0.41 mmol/L) were found to be higher than that in mothers. There were significant correlations between fetal and maternal PAAC. The total PAAC in mothers and fetuses, and its ratios were not changed with gestational age. In cases of SGA, essential amino acids' concentration (EAA), especially branch chain amino acid (BCAA) and lysine, decreased significantly. The feto-maternal ratios of EAA and BCAA were reduced significantly, whereas concentrations of EAA and BCAA in mothers did not change significantly. CONCLUSIONS: The results indicated that placental function and maternal nutrient supplement were important factors for maintaining fetal growth and development. In AGA cases, relationship of PAAC between mothers and fetuses were kept in a stable balance. In SGA fetuses certain amino acid metabolic disturbances existed. The reduction of some PAAC was not due to their decrease in mothers.

Amino Acids, Branched-Chain↗
PubMed1996

Cyclic AMP-dependent phosphodiesterase isozyme-specific potentiation by protein kinase C in hypertrophic cardiomyopathic hamster hearts.

We recently reported that protein kinase C (PKC) potentiates cAMP-dependent phosphodiesterase (PDE) activity in Syrian hamster hearts with hypertrophic cardiomyopathy (HCM) but not in control hamster hearts. In this study, we examined the mechanism of this PKC/PDE interaction by identifying the PDE isozyme that is the target of PKC modulation. Using Mono-Q high performance liquid chromatography, both control and HCM hamster cardiac PDE could be partially purified into the calcium/calmodulin-dependent (I), the cGMP-stimulated (II), and the low KM (III) isozyme fractions. The elution profiles of PDE isozyme fractions were similar to those in isolated hamster cardiac myocytes. The percentages of PDE isozymes activities (I/II/III) were 68.8:22.4:8.8% and 51.1:38.4:10.5% for HCM and control hearts, respectively (n = 4), suggesting a change in the quantitative expression of isozymes activities in HCM hearts with a significant increase in the calcium/calmodulin-dependent PDE isozyme activities (p < 0.05 compared with control). The addition of exogenous PKC (100 munits of rat brain) produced a 60% stimulation in the calcium/calmodulin-dependent PDE isozyme fraction but not in other PDE isozymes of HCM and in none of the isozymes in control hearts. This PKC-mediated potentiation of the calcium/calmodulin-dependent PDE activity was completely blocked by the PKC-specific peptide inhibitor PKC(19-31). Analysis of enzymatic kinetics showed that PKC enhanced the calcium/calmodulin-dependent PDE isozyme activity in HCM by increasing its Vmax (from 350 pmol/mg/min at baseline to 758 pmol/min/mg with PKC) without changing its KM (0.69 microM at baseline versus 0.89 microM with PKC). These results suggest that there are both quantitative and qualitative abnormalities in the expression of the calcium/ calmodulin-dependent PDE isozyme in HCM hearts and that the PKC modulation of PDE activity in the HCM heart is isozyme specific.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1996

The measurement of fingernail creatinine in the differentiation of acute from chronic renal failure.

It is often difficult to distinguish acute renal failure clinically from chronic renal failure, especially in patients who do not have records of their medical history. Since fingernail creatinine (Ncr) reflects serum creatinine at the time of nail formation, it has been suggested that the level of Ncr at the distal tip of the fingernail might represent the level of the serum creatinine about four months previously. In this study, clipped fingernail specimens from 60 normal individuals, 35 patients with chronic renal failure and 33 patients with renal insufficiency with rapid onset were analyzed for creatinine by a modified alkaline picrate method. The results showed that the Ncr level of the renal insufficiency with rapid onset group (69 + or - 12.39 mu mol/100 g nail) was similar to that in the normal group (62 + or - 10 mu mol/100 g nail) and significantly lower than that in the chronic renal failure group (130 + or - 35 mu mol/100 g nail, p <0.01). The correlation between Ncr and the serum creatinine level obtained four months previously was highly significant (r = 0.895, p <0.01). This study confirms that the Ncr measurement is of clinical value in differentiating acute from chronic renal failure.

Acute Kidney Injury↗
PubMed1996

Osteoclasts in normal and adjuvant arthritis bone tissues express the mRNA for both type I and II interleukin-1 receptors.

Osteoclasts are known to play a crucial role in both physiologic and pathologic bone resorption. Moreover, it is generally agreed that IL-1 has powerful effects on osteoclastic bone resorption, although the precise cellular sites and mechanisms by which IL-1 mediates osteoclastic bone resorption remain unclear. In particular, it is still controversial whether osteoclasts can respond to IL-1 directly. The expression of mRNA for type I IL-1 receptor (IL-1RI) and type II IL-1 receptor (IL-1RII) in osteoclasts was investigated in normal and inflammatory bone tissues by in situ hybridization to determine whether osteoclasts are the target cells for IL-1 and to elucidate the mechanism by which IL-1 induces osteoclastic bone resorption. For this study, normal tibiae were obtained from newborn, young, and adult mice and rats, and inflammatory bone tissues with bone destruction were obtained from adjuvant arthritis rat models. The results showed that (a) both IL-1 receptors (IL-1RI and -II) mRNA were expressed by osteoclasts in all tissue sections of normal tibiae; (b) at the stage of the adjuvant arthritis studied, the IL-1RI mRNA was the most predominant message in osteoclasts present in the area with serious cartilage and bone destruction, whereas the expression level of IL-1RII mRNA in these osteoclasts was weak; and (c) both IL-1RI and -II mRNA were expressed by osteoblasts, as well as by osteocytes localized in the osteoid. In addition, these messages were also expressed by chondrocytes, but the signals were not detected in the chondrocytes in the zones of hypertrophy and provisional calcification. Our present study demonstrates for the first time that mouse and rat osteoclasts express IL-1RI and -II mRNA, which suggest that a primary effect of IL-1 on osteoclasts may be one of the mechanisms by which IL-1 mediates normal bone remodeling and pathologic bone resorption in chronic inflammatory diseases.

Animals↗
PubMed1996

Prostate-specific antigen levels in nipple aspirate fluid correlate with breast cancer risk.

Despite the fact that breast cancer is the most common non-cutaneous cancer and a leading cause of cancer deaths in women, accepted markers of breast cancer risk miss up to 40% of these tumors. Moreover, screening methods involving the analysis of tissue or cells are limited by the need for a surgical biopsy. Nipple aspiration is a quick, efficient, noninvasive method to obtain breast epithelial cells, the cells at risk for transformation to carcinoma. Prostate-specific antigen (PSA), a protein thought to be specific to the prostate but recently found in a subset of breast tumors, has been correlated with improved survival. The purpose of this study was to measure PSA in a group of women with increasing breast cancer risk (no risk or family history of breast cancer, precancerous mastopathy, and invasive cancer) and determine if PSA correlates with risk. Nipple aspirate fluid was obtained from the intact breast and from surgical specimens using a modified breast pump. PSA was then measured in the fluid using a highly sensitive and specific immunofluorometric procedure. PSA was found at levels ranging from 0-13,423 ng/g of total protein, and there was a significant relationship between PSA level and breast cancer risk (P = 0.001). That is, all women with no risk factors and 90% of those with a family history had high PSA levels, whereas 68% of subjects with precancerous mastopathy or invasive cancer had low PSA levels. PSA was higher in premenopausal subjects (P = 0.002). After adjusting for the effect of menopausal status, there remained a significant association between PSA and breast cancer risk. These findings suggest that PSA in nipple aspirate fluid may be a useful marker of breast cancer risk.

Adult↗
PubMed1996

Relative contribution of polar interactions and conformational compatibility to the binding of neurokinin-1 receptor antagonists.

Based on single residue substitutions, previous studies suggested that Gln165, His197, and His265 of the neurokinin-1 receptor interact directly with many nonpeptide antagonists, including CP-96,345. To further test this model, all three residues have been substituted simultaneously with alanine. The Q165A-H197A-H265A triple mutant bound CP-96,345 and eight analogs with similar affinity (2-20 microM), even though the same series of compounds bound to the wild-type receptor with affinities over a range of 1000-fold. These observations correspond exactly to the prediction of the binding site model. The micromolar binding affinity of all tested CP-96,345 analogs for the triple mutant seems to reflect solely van der Waals interactions, which suggests a significant contribution of conformational compatibility (or shape complementarity) to binding affinity. The primary role of conformational compatibility in ligand binding was consistent with the observation that simply transferring the residues involved in polar interactions with beta2-agonists into the neurokinin-1 receptor did not lead to increased binding affinity for the beta2-agonists. Taken together, these results support a general principle of ligand-receptor binding in which specific polar interactions can take place only if the overall ligand conformation is compatible with the stereochemistry of the binding pocket. In addition, double-residue and triple-residue substitutions, in combination with single-residue substitutions, can provide an alternative route to reveal multiple interactions that may not be detectable by single-residue substitutions and represent a novel approach to examine ligand-receptor interactions in the absence of high-resolution structural data.

Amino Acid Sequence↗
PubMed1996

[The relation between indirect fetal electrocardiogram and blood gas analysis of umbilical cord artery during labor].

OBJECTIVE: To observe the relation between indirect fetal electrocardiogram (FECG) and blood gas analysis of umbilical cord artery blood during labor and discuss the possibility of using FECG for labor monitoring. METHODS: Indirect FECG was used for fetal monitoring in 80 cases during the second stage of labor and cord umbilical artery blood was taken immediately after delivery for blood gas analysis. Cases were retrospectively divided into normal and abnormal groups according to the results of FECG. RESULTS: The success rate of FECG test was 91.95%. Significant differences were noted in mean values of pH, PCO2, PO2, actual base excess (ABE) and standard base excess (SBE) of umbilical artery between the 2 groups, so were the percentages of cases with pH < 7.20, PCO2 > 8.00 kPa, PO2 < 2.10 kPa. CONCLUSIONS: Indirect FECG can be used for fetal monitoring during labor. FECG is obviously correlated with acid-base equilibrium and blood gas concentration of umbilical cord artery blood, it is a sensitive index of fetal and neonatal hypoxia.

Adult↗
PubMed1996

[Clinical significance of changes of urinary enzymes in pregnancy induced hypertension].

OBJECTIVE: To study the clinical significance of changes of N-acetyl-beta-D-glucosaminidase (NAG) and lysozyme in random urine sample in pregnancy induced hypertension (PIH). METHODS: The concentration of NAG was measured by oronitrophenol spectrophotometric methods, and the concentration of lysozyme by agar plate diffusion method. Random urine samples from 266 pregnant women were examined, 110 cases were normal pregnant women, 156 cases were PIH patients. RESULTS: (1) The level of NAG and lysozyme in moderate and severe PIH patients were significantly higher than that in mild PIH patients and normal pregnant women (P < 0.01) and it increased with the severity of disease. (2) There was a positive correlation between NAG and protein/creatinine (Pr/Cr) ratio in random urine. (3) There was a positive correlation between urinary lysozyme and serum beta 2-microglobulin (r = 0.874, P < 0.05). CONCLUSION: Determination of urinary NAG and lysozyme levels will differentiate various states of PIH.

Acetylglucosaminidase↗
PubMed1995

Biochemical characterization and posttranslational modification of AlgU, a regulator of stress response in Pseudomonas aeruginosa.

AlgU is homologous to the extreme heat shock sigma factor sigma E from enteric bacteria. In this work, AlgU was overproduced and purified and its function investigated at the biochemical level. AlgU was shown to associate with RNA polymerase and direct transcription of a target promoter. AlgU also exhibited multiple isoforms detected by 2D gel analysis. Treatment with a Ser/Thr phosphatase shifted the distribution of isoforms towards the basic side on 2D gels, suggesting that posttranslational modifications of AlgU may involve phosphorylation. The underphosphorylated forms of AlgU copurified with RNA polymerase. It is possible that phosphorylation affects AlgU activity or its stability.

Amino Acid Sequence↗
PubMed1995

A general method for mapping tertiary contacts between amino acid residues in membrane-embedded proteins.

A general method for mapping tertiary interactions in membrane proteins using the visual pigment rhodopsin as a model is presented. In this approach, the protein is first assembled from two separately expressed gene fragments encoding nonoverlapping segments of the full-length polypeptide. Cys residues are then introduced into each of the two fragments such that juxtaposed residues are able to form disulfide cross-links in the protein either spontaneously or with the assistance of a Cu(2+)-(phenanthroline)3 oxidant. The cross-linked polypeptides are identified from a characteristic mobility shift on sodium dodecyl sulfate (SDS) gels as detected by Western blot analysis where the covalently bound heterodimer migrates with a mobility essentially identical to that of the native, full-length protein. Three different split rhodopsin mutants were prepared: one with a split in the loop connecting helices 3 and 4 (the 3/4 loop), one with a split in the 4/5 loop, and one with a split in the 5/6 loop. Each of these proteins when purified from transfected COS cells bound 11-cis-retinal, had a native absorption maximum at 500 nm, and activated transducin in a light-dependent manner. The cross-linking assay was tested with the rhodopsin mutant split in the 5/6 loop using the rho-1D4 antibody (which recognizes the carboxy terminal eight amino acids of rhodopsin) to detect the proteins on Western blots of SDS gels. Cys residues were substituted for Val-204 in the amino terminal fragment and Phe-276 in the carboxy terminal fragment of the rhodopsin mutant because Schwartz and co-workers [Elling et al.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1995

Recognition of type 1 chain oligosaccharides and lacto-series glycolipids by an antibody to human secretory component.

Binding of the mouse IgM antibody 6C4 is lost after treatment of human free secretory component with peptide N-glycosidase F (Bakos et al. (1991) J. Immunol. 146, 162-168) or periodate, suggesting that asparagine-linked oligosaccharides contain the epitope recognized by this antibody. Inhibition of antibody binding to free secretory component by milk oligosaccharides established that lacto-N-tetraose is the minimum structure recognized by the antibody, but larger oligosaccharides with terminal Gal beta 1-3GlcNAc sequences bind with much higher affinity. Antibody binding is enhanced by substitution with the Lewis Fuc alpha 1-4 and is inhibited by Fuc alpha 1-2Gal substitution. Free secretory component, however, does not bind other antibodies that recognize Le(a) or Leb oligosaccharides, and binding is lost after digestion with a beta-galactosidase that cleaves Gal beta 1-3 linkages but not after digestion with alpha-L-fucosidase. Therefore, the major epitope recognized by 6C4 on free secretory component is probably not an asparagine-linked Le(a) oligosaccharide. The antibody also binds to human milk lactoferrin, some human mucins, and lacto-series glycolipids including III4 alpha Fuc-lactotetraosyl ceramide and lactotetraosyl ceramide. Based on affinity chromatography of oligosaccharides released from free secretory component, the epitope recognized by antibody 6C4 is present on approximately 3.5% of the asparagine-linked oligosaccharides.

Animals↗
PubMed1995

Isolation and sequencing of two cDNA clones encoding rat spleen cathepsin E and analysis of the activation of purified procathepsin E.

Cathepsin E (CE) is an intracellular, nonlysosomal aspartic proteinase consisting of two identical subunits with a molecular mass of approximately 42 kDa and has a unique subcellular distribution in various rat tissues. In this study, we determined the complete amino acid sequence of rat spleen CE and examined the activation mechanism of the proenzyme purified from this tissue. Two cDNA clones encoding rat CE, termed pTN05 and pTN1, were isolated. Comparison of the amino acid sequences predicted from the respective cDNA sequences revealed that they were essentially identical, except that pTN1 lacked a sequence corresponding to residues Tyr293-Pro325 of the longer cDNA clone (pTN05). Based on the structural analysis of purified enzyme forms, the CE precursor was found to comprise a signal peptide, a prosequence, and a mature protein region of 19, 39, and 337 (pTN05) or 304 (pTN1) residues, respectively. Despite a high degree of similarity in the overall structure of CE between rat and other mammalian species, the first 11 residues in the NH2-terminal sequence of rat mature enzyme were significantly different from those of other species. The purified pro-CE was analyzed for its conversion to the mature form. The results indicated that the maximal conversion occurred at pH 3.0-4.0 in a temperature- and time-dependent manner by autocatalytic cleavage at the site between Phe39-Ser40. This conversion was highly dependent on the protein concentrations of pro-CE and delayed by the presence of exogenous substrates, suggesting the predominance of intermolecular reaction for its conversion to the mature form.

Amino Acid Sequence↗