PubMed Health⌕ Search

Biomedical subjects

K Liu

Publications and source records attributed to K Liu.

At least 19 recordsLinked to original sources
PubMed1999

Association of nonspecific minor ST-T abnormalities with cardiovascular mortality: the Chicago Western Electric Study.

CONTEXT: Minor electrocardiographic (ECG) ST-T abnormalities are common, but their prognostic importance has not been fully determined. OBJECTIVE: To examine associations of single (1 time only) and multiple (2 times only and > or =3 times) nonspecific minor ST-T abnormalities in 5 years with long-term mortality due to myocardial infarction (MI), coronary heart disease (CHD), cardiovascular disease (CVD), and all causes in middle-aged men. DESIGN: Prospective cohort study (29-year follow-up after 5 annual examinations). SETTING AND PARTICIPANTS: A total of 1673 men employed at the Western Electric Company in Chicago, III, aged 40 to 55 years at entry, with no evidence of CHD and no major ECG abnormalities throughout the first 5-year period. MAIN OUTCOME MEASURES: Minor ST-T abnormalities identified from annual resting ECGs and mortality ascertained from death certificates. RESULTS: Of the 1673 men, 173 had evidence of isolated nonspecific minor ST-T segment abnormalities. During the follow-up period, there were 234 deaths due to MI, 352 deaths due to CHD, 463 deaths due to CVD, and 889 deaths due to all causes. For men with 3 or more annual recordings of minor ST-T abnormalities, risk of death due to MI, CHD, CVD, and all causes was significantly greater than for those with normal ECG findings. For men with 3 or more ECGs with minor ST-T abnormalities, relative risks (and 95% confidence intervals) adjusted for cardiovascular and other risk factors were 2.28 (1.16-4.49), 2.39 (1.39-4.12), 2.30 (1.44-3.68), and 1.60 (1.06-2.42), respectively, with a graded relationship between frequency of occurrence of ST-T abnormalities and mortality risk (linear trend, P< or =.007). CONCLUSIONS: Persistent, minor, nonspecific ST-T abnormalities are associated with increased long-term risk of mortality due to MI, CHD, CVD, and all causes; the higher the frequency of occurrence of minor ST-T abnormalities, the greater the risk. These data underscore the potential value of including nonspecific ECG findings in the overall assessment of cardiovascular risk.

Adult↗
PubMed1999

Evidence for heat shock protein immunity in a rat cardiac allograft model of chronic rejection.

BACKGROUND: The stress response to injury concept has been proposed as a mechanism of chronic rejection. This hypothesis has been tested with a rat cardiac allograft model in recipients pretreated with donor bone marrow (BM) cells. Chronic rejection is manifested in this BM group by obliterative arteriopathy and the epicardium and endocardium contains lymphocytic infiltrates resembling Quilty lesions. Pretreatment with a liver allograft (the orthotopic liver transplant [OLTx] group) is associated with an absence of chronic rejection in the transplanted heart. METHODS AND RESULTS: . Stress responses in the allograft were assessed by determining heat shock protein (hsp) expression by immunohistology of graft tissues and immunoblot analysis of stromal tissue lysates with monoclonal antibodies (mAb) to mammalian hsp60, the inducible hsp72, the constitutively expressed hsc73, and the grp78 C-terminal sequence KSEKDEL (grp78seq). Immunostaining showed clusters of grp78seq-positive cells in the inflammatory infiltrates of obliterated blood vessels and Quilty lesions in the BM group of cardiac allografts. Such grp78seq-positive cells were not seen in the OLTx group of heart allografts nor in syngrafts. Neither group showed significantly different graft myocyte staining of grp78 or hsp72, whereas hsp60 and hsc73 showed higher expression in the BM group and, to a lesser extent, the OLTx group. The increased expression of hsc73 was seen especially in the obliterated arteries and in myocytes nearby cellular infiltrates. Immunoblot analysis of graft stromal tissue lysates showed additional bands with mAb to hsp60 and hsc73 for the OLTx and especially the BM group. No significant bands were seen for hsp72 and grp78. Lymphocytes isolated from chronically rejecting allografts reacted with irradiated autologous spleen cells in the presence of mycobacterial hsp65 and interleukin-2. Culturing of graft-infiltrating cells with mycobacterial hsp71 and interleukin-2 yielded lymphocyte clones without alloreactivity, but with strong proliferative responsiveness to self-antigen-presenting cells and, only in the presence of mycobacterial hsp71 or murine grp78. This T-cell reactivity seemed to require intact hsp molecules because treatment of hsp71 with proteolytic enzymes, polymyxin, or ATP abrogated this induction of the stimulatory effect of self-antigen-presenting cells. These T cells are similar to the hsp-dependent, autoreactive lymphocytes cloned from acutely rejecting rat allografts. CONCLUSIONS: These findings support the concept that the pathogenesis of chronic rejection involves a stress response and the participation of graft-infiltrating autoreactive T cells that operate under hsp-dependent mechanisms.

Animals↗
PubMed1999

Diagnosis of posttransplant granulocytic sarcoma by fine-needle aspiration cytology and flow cytometry.

We describe a patient who developed granulocytic sarcomas of the mesentery and breast approximately 4 yrs following an allogenic bone marrow transplantation for acute myeloblastic leukemia. The diagnosis was made by a combination of fine-needle aspiration cytology and flow cytometry. The differential diagnoses of localized masses in posttransplant patients and how the combination of fine-needle aspiration cytology and flow cytometry may be used are discussed.

Adult↗
PubMed1999

Ten-year incidence of elevated blood pressure and its predictors: the CARDIA study. Coronary Artery Risk Development in (Young) Adults.

Few prospective studies have examined associations of lifestyle factors or variables in the insulin resistance syndrome (syndrome X) with incidence of elevated blood pressure (BP) in black subjects and women. This report estimates the 10-year incidence of high blood pressure (HBP) and high normal blood pressure (HNBP) in the biracial cohort of the Coronary Artery Risk Development in (Young) Adults Study (CARDIA), and examines lifestyle factors and four syndrome X variables, measured at baseline, as predictors. CARDIA examined 5115 black and white men and women aged 18-30 years in 1985-1986, and re-examined them at 2, 5, 7, and 10 years. The 10-year incidence of HBP was 16.4% in black men, 7.8% in white men, 13.1% in black women, and 3.2% in white women, while the 10-year incidence of HBP or HNBP was 29.5%, 16.2%, 19.2%, and 6.3%, respectively, in the four sex-race subgroups. Predictors included body mass index, waist circumference, physical activity, alcohol intake, pulse rate, cigarette smoking, education, fasting insulin, triglycerides, uric acid, and high-density lipoprotein cholesterol, as well as age and systolic BP. In univariate analyses, each of these variables was significantly related to incidence in at least one of the four sex-race groups. In multivariate analyses that included control for age and systolic pressure, independent predictors included fasting insulin in white men and women, triglycerides in white men, uric acid and pulse rate in black men, waist circumference in white men and black women, and education (inverse) in white men and black and white women. These results suggest that lower socioeconomic status, as assessed by education level, and one or more syndrome X variables, ie, fasting insulin, triglycerides, uric acid, may be associated with development of elevated BP in young adults.

Adult↗
PubMed1999

Risk factors for falls in hospitalized older medical patients.

BACKGROUND: The incidence of falls among older hospitalized patients is higher than that of community-dwelling older persons. Prevention is important, but factors associated with these falls are less well studied than falls occurring in the community or nursing homes. METHODS: This study was conducted in an acute-care general hospital in Hong Kong. During November 1995 to March 1997, all older inpatients who fell during hospitalization were assessed by a geriatrician, a physiotherapist, and an occupational therapist. A standardized protocol to study the clinical and performance-oriented functional factors was employed. A sex- and age-matched hospital control was recruited for each case. In total, 51 cases and controls (mean ages 77.8 +/- 7.3 years and 77.5 +/- 7.0 years, respectively) were studied. RESULTS: Among the multiple clinical and functional risk factors for falls identified, lower limb weakness (i.e., power less than MRC grade 4 in one or both lower limbs) and poor tandem walk ability emerged as two significant predictive factors for falls in the hospital. The overall classification accuracy of fallers and nonfallers was 79%. The sensitivity was 84% and specificity was 75%. Clinical factors were the underlying causes for the lower limb weakness and poor tandem walk performance. CONCLUSIONS: Among clinical and functional risk factors for falls in the older medical patient, lower limb weakness and poor tandem walk ability were most predictive. Falls prevention programs in hospitals should employ these two tests as screening instruments.

Accidental Falls↗
PubMed1999

Heart rate and subsequent blood pressure in young adults: the CARDIA study.

The objective of the present study was to examine the hypothesis that baseline heart rate (HR) predicts subsequent blood pressure (BP) independently of baseline BP. In the multicenter longitudinal Coronary Artery Risk Development in Young Adults study of black and white men and women initially aged 18 to 30 years, we studied 4762 participants who were not current users of antihypertensive drugs and had no history of heart problems at the baseline examination (1985-1986). In each race-sex subgroup, we estimated the effect of baseline HR on BP 2, 5, 7, and 10 years later by use of repeated measures regression analysis, adjusting for baseline BP, age, education, body fatness, physical fitness, fasting insulin, parental hypertension, cigarette smoking, alcohol consumption, oral contraceptive use, and change of body mass index from baseline. The association between baseline HR and subsequent systolic BP (SBP) was explained by multivariable adjustment. However, HR was an independent predictor of subsequent diastolic BP (DBP) regardless of initial BP and other confounders in white men, white women, and black men (0.7 mm Hg increase per 10 bpm). We incorporated the part of the association that was already present at baseline by not adjusting for baseline DBP: the mean increase in subsequent DBP was 1.3 mm Hg per 10 bpm in white men, white women, and black men. A high HR may be considered a risk factor for subsequent high DBP in young persons.

Adolescent↗
PubMed1998

Association of apolipoprotein E phenotype with plasma lipoproteins in African-American and white young adults. The CARDIA Study. Coronary Artery Risk Development in Young Adults.

Apolipoprotein E phenotype (APOE phenotype) has been demonstrated to be a genetic determinant of cardiovascular disease. This atherogenicity may be a reflection of the association of APOE phenotype and plasma lipoprotein concentrations. The Coronary Artery Risk Development in Young Adults (CARDIA) Study affords the opportunity to assess the frequency of apolipoprotein E alleles in population-based samples of African Americans and whites in the United States and to compare the associations of APOE phenotype with lipoprotein and apoprotein concentrations. Data from 3,485 African-American and white men and women between the ages of 25 and 37 years who attended the fourth CARDIA Study examination in 1992-1993 were used in this analysis. African-American men and women had significantly higher frequencies of E2 and E4 phenotype and thus higher frequencies of *epsilon2 and *epsilon4 alleles (p < 0.005). Men and women of both races with APOE4 phenotype generally had higher low density lipoprotein cholesterol, apolipoprotein B, and lipoprotein(a) concentrations and lower high density lipoprotein cholesterol concentration, and individuals with APOE3 phenotype had the lowest triglyceride concentration. Major differences between African Americans and whites were observed in the distribution of APOE phenotypes and *epsilon alleles, but APOE phenotype was associated with similar differences in lipoprotein and apoprotein concentrations in both races. The data suggest that APOE phenotype may be a risk factor for cardiovascular disease in both African Americans and whites because it is associated similarly with an adverse lipoprotein profile.

Adolescent↗
PubMed1998

Benefit of a favorable cardiovascular risk-factor profile in middle age with respect to Medicare costs.

BACKGROUND: People without major risk factors for cardiovascular disease in middle age live longer than those with unfavorable risk-factor profiles. It is not known whether such low-risk status also results in lower expenditures for medical care at older ages. We used data from the Chicago Heart Association Detection Project in Industry to assess the relation of a low risk of cardiovascular disease in middle age to Medicare expenditures later in life. METHODS: We studied 7039 men and 6757 women who were 40 to 64 years of age when surveyed between 1967 and 1973 and who survived to have at least two years of Medicare coverage in 1984 through 1994. Men and women classified as being at low risk for cardiovascular disease were those who had the following characteristics at the time they were initially surveyed: serum cholesterol level, <200 mg per deciliter (5.2 mmol per liter); blood pressure, < or =120/80 mm Hg; no current smoking; an absence of electrocardiographic abnormalities; no history of diabetes; and no history of myocardial infarction. We compared Medicare costs for the 279 men (4.0 percent) and 298 women (4.4 percent) who had this low-risk profile with those for the rest of the study group, who were not at low risk. Health Care Financing Administration charges for services to Medicare beneficiaries were used to estimate average annual health care costs (total costs, those for cardiovascular diseases, and those for cancer). RESULTS: Average annual health care charges were much lower for persons at low risk - the total charges for the men at low risk were less than two thirds of the charges for the men not at low risk ($1,615 less); for the women at low risk, the charges were less than one half of those for the women not at low risk ($1,885 less). Charges related to cardiovascular disease were lower for the low-risk groups of men and women than for those not at low risk (by $979 and $556, respectively), and charges related to cancer were also lower (by $134 and $189). CONCLUSIONS: People with favorable cardiovascular risk profiles in middle age had lower average annual Medicare charges in older age. Having optimal status with respect to major cardiovascular risk factors may result not only in greater longevity but also in lower health care costs.

Adult↗
PubMed1998

Nascent RNA in transcription complexes interacts with CspE, a small protein in E. coli implicated in chromatin condensation.

Proteins in a partially fractionated Escherichia coli extract that interact with the nascent RNA in active transcription complexes from several promoters were detected using the photocrosslinking ribonucleotide analogs 5-(azidophenacyl)thio-UTP or 5-(azidophenacyl)thio-CTP as transcription substrates. Upon irradiation of ternary transcription complexes, several extract proteins were crosslinked to the RNA. Most notably, a small protein was crosslinked to the RNA in complexes on seven of nine templates tested. This protein was purified and sequenced and found to match a hypothetical protein, MsmC/CspE, recently shown to be involved in chromatin partitioning. CspE has 69% amino acid sequence identity with the major cold shock protein in E. coli, CspA, which has been shown to bind to a DNA sequence designated the Y box, with the sequence 5'-ATTGG. Of the nine templates tested, CspE was found to be most heavily crosslinked to RNA from the lambda PR' promoter, which is modified by the Q antiterminator protein. CspE was very heavily crosslinked to RNA only ten nucleotides long in initial ternary complexes on this promoter, but not to this same RNA after it had been released from the transcription complex. However, even when present from the start of transcription, CspE did not crosslink to the RNA 82 nucleotides long in elongation complexes from this same promoter. Despite the loss of interaction with the RNA after polymerase had left the promoter, CspE inhibited Q-mediated transcriptional antitermination from PR' in vitro almost 200 nucleotides downstream from the promoter, presumably by interaction with the Y box DNA upstream from PR', which overlaps with the binding site for the Q. A potential role for CspE and transcription in chromosome condensation and nucleoid structure is discussed.

Amino Acid Sequence↗
PubMed1998

Fine-needle aspiration: comparison of smear, cytospin, and cell block preparations in diagnostic and cost effectiveness.

We compared the results of smears to those of cytospin and cell block preparations from fine-needle aspirations to determine the cost effectiveness of each and to determine which should be routinely obtained. We reviewed 844 cases, 361 of which had both smears and cytospins, and 483 of which had both smears and cell blocks. Smears alone were diagnostic in 94% of cases (796/844 cases), cytospins alone diagnostic in 43% of cases (154/361 cases), and cell blocks alone diagnostic in 57% of cases (277/483 cases). Cytospins contributed additional information beyond that obtained from smears in 2% (7/361) and cell blocks in 12% (57/483) of cases. When smears were nondiagnostic, cytospins contributed additional information in 10% (2/21) of cases and cell blocks contributed additional information in 44% (12/27) of cases. The cost of providing a diagnosis from smear alone is $212, from cytospin alone is $352, and from cell block alone is $392. The cost for additional information established by cytospin is $7,736 and by cell block the cost is $1,906. Smears are superior to either cytospins or cell blocks in providing a diagnosis. It is not cost-effective to obtain either cytospins or cell blocks in addition to smears on all cases. However, it is cost-effective to obtain cell blocks when the immediate smear evaluation is nondiagnostic.

Biopsy, Needle↗
PubMed1998

PRAK, a novel protein kinase regulated by the p38 MAP kinase.

We have identified and cloned a novel serine/ threonine kinase, p38-regulated/activated protein kinase (PRAK). PRAK is a 471 amino acid protein with 20-30% sequence identity to the known MAP kinase-regulated protein kinases RSK1/2/3, MNK1/2 and MAPKAP-K2/3. PRAK was found to be expressed in all human tissues and cell lines examined. In HeLa cells, PRAK was activated in response to cellular stress and proinflammatory cytokines. PRAK activity was regulated by p38alpha and p38beta both in vitro and in vivo and Thr182 was shown to be the regulatory phosphorylation site. Activated PRAK in turn phosphorylated small heat shock protein 27 (HSP27) at the physiologically relevant sites. An in-gel kinase assay demonstrated that PRAK is a major stress-activated kinase that can phosphorylate small heat shock protein, suggesting a potential role for PRAK in mediating stress-induced HSP27 phosphorylation in vivo.

Amino Acid Sequence↗
PubMed1998

A novel palindromic triple-stranded structure formed by homopyrimidine dodecamer d-CTTCTCCTCTTC and homopurine hexamer d-GAAGAG.

We have carried out NMR and molecular mechanics studies on a complex formed when a palindromic homopyrimidine dodecamer (d-CTTCTCCTCTTC) and a homopurine hexamer (d-GAAGAG) are mixed in 1:1 molar ratio in aqueous solutions. Such studies unequivocally establish that two strands of each oligomer combine to form a triple-stranded DNA structure with a palindromic symmetry and with six T.A:T and six C+. G:C hydrogen-bonded base triads. The two purine strands are placed head to head, with their 3' ends facing each other in the center of the structure. One-half of each pyrimidine strand contains protonated and the other half contains non-protonated cytosines. The two half segments containing protonated cytosines are hydrogen bonded to each of the two purine hexamers through Hoogsteen T.A and C+.G base pairing. The segments containing non-protonated cytosines are involved in Watson-Crick (A:T and G:C) base pairing. This leads to a palindromic triplex with a C2-dyad symmetry with respect to the center of the structure. The complex is less stable at neutral pH, but the cytosines involved in Hoogsteen base pairing remain protonated even under these conditions. Molecular mechanics calculations using NMR constraints have provided a detailed three-dimensional structure of the complex. The entire stretches of purine, and the pyrimidine nucleotides have a conformation close to B-DNA.

Base Composition↗
PubMed1998

Improvement of ischemic damage in gerbil hippocampal neurons by procaine.

Acute cerebral ischemia induces membrane depolarization in the neuron, thereby incurring the simultaneous influx of various ions such as Na+ and Ca2+. Since procaine possesses the ability to inhibit the release of Ca2+ from intracellular Ca2+ stores to the cytosol as well as the ability to block Na+ channels, the effects of procaine on ischemia were investigated in the present study in gerbils both in vivo and in vitro. The histologic outcome was evaluated 7 days after 3 min of transient forebrain ischemia by assessing delayed neuronal death in hippocampal CA1 pyramidal cells in animals administered procaine (0.2, 0.4, or 2 micromol) intracerebroventricularly 10 min before ischemia and in animals given saline. The changes in the direct-current potential shift in the hippocampal CA1 area were measured using an identical animal model. A hypoxia-induced intracellular Ca2+ increase was evaluated by in vitro microfluorometry in gerbil hippocampal slices, and the effects of procaine (10, 50, and 100 micromol/l) on the Ca2+ accumulation were examined. Additionally, the effect of procaine (100 micromol/l) in a Ca2+-free condition was investigated. The histologic outcome was improved and the onset of the ischemia-induced membrane depolarization was prolonged by the preischemic administration of procaine. The increase in the intracellular concentration of Ca2+ induced by the in vitro hypoxia was suppressed by the perfusion of procaine-containing mediums (50 and 100 micromol/l), regarding both the initiation and the extent of the increase. A hypoxia-induced intracellular Ca2+ elevation in the Ca2+-free condition was observed, and the perfusion with procaine (100 micromol/l) inhibited this elevation. Procaine helps protect neurons from ischemia by suppressing the direct-current potential shift and by inhibiting the release of Ca2+ from the intracellular Ca2+ stores, as well as by inhibiting the influx of Ca2+ from the extracellular space.

Anesthetics, Local↗
PubMed1998

Catalytic domain of the p120 Ras GAP binds to RAb5 and stimulates its GTPase activity.

Ras is a master GTPase switch controlling multiple signal transduction cascades in the regulation of cell proliferation and differentiation. Rab5 is a local GTPase switch that is localized on early endosomes and controls early endosome fusion. This study demonstrates that the catalytic domain of p120 GTPase-activating protein (GAP), a well known Ras GAP, is able to interact physically with Rab5 and stimulate its GTPase activity. This GAP activity toward Rab5, however, cannot be extended to other Rab GTPases such as Rab3, Rab4, and Rab6, indicating that it is not a generic GAP for the Rab family of GTPases that regulate intracellular membrane fusion during endocytosis and exocytosis. The findings indicate a level of structural similarity between Ras and Rab5 unexpected from their primary sequences. They also suggest a possible signal transduction regulation of the Rab5-dependent endosome fusion via the Ras GAP.

Catalysis↗
PubMed1998

Kinetics of uptake and elimination of silicic acid by a human subject: a novel application of 32Si and accelerator mass spectrometry.

Silicon is possibly important in human physiology in protecting against the toxic effects of aluminium, but the kinetics of uptake and excretion of silicic acid, the bioavailable form, are not well characterised. We have used 32Si as a tracer in a human uptake experiment to determine a gastrointestinal uptake factor for silicic acid, and to elucidate the kinetics of renal elimination. Urine collections were made for extending intervals from 2 to 12 h over 2 days following ingestion by a single human subject of a neutral silicic acid solution containing tracer levels of 32Si (t1/2 approximately 150 y). Silicon was isolated as SiO2 and the 32Si content determined by accelerator mass spectrometry (AMS), using a gas-filled magnet technique to eliminate a prolific isobaric interference from 32S. Silicon uptake appears to have been essentially complete within 2 h of ingestion. Elimination occurred by two simultaneous first-order processes with half-lives of 2.7 and 11.3 h, representing around 90% and 10%, respectively, of the total output. The rapidly eliminated 32Si was probably retained in the extracellular fluid volume, whilst the slower component may represent intracellular uptake and release. Elimination of absorbed 32Si was essentially complete after 48 h and was equivalent to 36% of the ingested dose. This establishes only a lower limit for gastrointestinal absorption as, although there was no evidence for longer term retention of additional 32Si, the possibility could not be excluded by these results.

Administration, Oral↗
PubMed1998

Demonstration of myxoid change in fine-needle aspiration of synovial sarcoma: a case report.

We report a case of synovial sarcoma with extensive myxoid change diagnosed by fine-needle aspiration. The patient is a 46-year-old woman who presented with a right paratibial mass. Aspiration cytology demonstrated a spindle cell neoplasm consistent with a synovial sarcoma but containing a prominent myxoid matrix. The clinical suspicion and cytologic diagnosis of a synovial sarcoma was confirmed by histologic and immunohistochemical findings. The cytologic differential diagnosis of spindle cell neoplasms with extensive myxoid change should be broadened to include synovial sarcoma.

Biomarkers, Tumor↗