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Biomedical subjects

K Liu

Publications and source records attributed to K Liu.

At least 127 records · Page 7Linked to original sources
PubMed2000

Lower ankle/brachial index, as calculated by averaging the dorsalis pedis and posterior tibial arterial pressures, and association with leg functioning in peripheral arterial disease.

OBJECTIVE: We compared three commonly used methods of ankle/brachial index (ABI) calculation to determine their relative association with objective measures of leg functioning in peripheral arterial disease. METHOD: The study design was cross-sectional; the setting was an academic medical center. The participants were 244 men and women, aged 55 years and older, with and without peripheral arterial disease, from a noninvasive vascular laboratory and a general medicine practice. The main outcome measures were walking velocity and endurance, measured with the 4-m walk and the 6-minute walk, respectively. Three methods of ABI calculation were assessed: using the highest arterial pressure within each leg (method #1), using the lowest pressure in each leg (method #2), and averaging the dorsalis pedis and posterior tibial pressures within each leg (method #3). For each method, we established the prevalence of peripheral arterial disease. We then used regression analyses to identify the ABI calculation method most closely associated with leg functioning. The ABI with the greatest statistical significance and largest regression coefficient was considered most closely associated with leg functioning. RESULTS: Peripheral arterial disease prevalence ranged from 47% when method #1 was used to 59% when method #2 was used. When the right and left legs were compared, the leg with the lower ABI, as identified through use of method #3, was most associated with leg functioning. Within the leg with the lower ABI, method #3 was more closely associated with 6-minute walk distance (regression coefficient = 811.5 feet per 1 unit ABI; P<.001) and 4-m walking velocity (regression coefficient = 0.353 m/s per 1 unit ABI; P<.001) than method #1 or method #2. CONCLUSION: The lower ABI, determined by averaging the dorsalis pedis and posterior tibial arterial pressures in each leg, is most predictive of walking endurance and walking velocity in peripheral arterial disease.

Aged↗
PubMed2000

Comparison of the stress response to cryopreservation in monolayer and three-dimensional human fibroblast cultures: stress proteins, MAP kinases, and growth factor gene expression.

Stress responses induced in fibroblasts by cryopreservation were compared in suspension or three-dimensional cultures at various times up to 5 days of recovery. Cryopreservation caused an 86% inhibition in [(35)S]methionine incorporation, with recovery over 2 days to 45% &plusmn: 14% of its original value. Stress proteins, including heat shock protein (hsp) and glucose-regulated proteins (GRP), detected by immunoblotting, responded with transient increases in cellular content (hsp27 and hsp90 in suspension and three-dimensional culture, and hsp70 only in three-dimensional culture), decreases at 24 h (hsp56, hsp70, hsp90, and GRP78 in three-dimensional culture and hsp90 in suspension), or little change (hsp70 in suspension). Polyacrylamide gel electrophoresis of [(35)S]methionine-labeled proteins showed transient induction of hsp47 within 4 h, and increased synthesis of hsp90 and GRP78 and other unidentified proteins at 24 h, but no change in hsp70. The mitogen-activated protein (MAP) kinase, p38, showed a transient increase after thawing, followed by a peak in extracellular signal-regulated kinase at 24 h. The stress-activated protein kinase (JNK) was not activated. In both stress protein and MAP kinase responses, the three-dimensional cultures showed a more intense response than fibroblasts in suspension. Although some responses were related to osmotic and cold stress during freezing, others were unique. Cryopreservation induced mRNA for selected growth factors, including vascular endothelial growth factor (VEGF) and platelet-derived growth factor (PDGF) A chain, which increased 5- to 20- fold at 48 h returning to basal levels by 120 h. Our results indicate the novel finding that cryopreservation of fibroblasts grown in three-dimensional culture induced a specific cellular stress response including growth factors.

Cell Culture Techniques↗
PubMed2000

Changes in home care use by disabled elderly persons: 1982-1994.

OBJECTIVES: The use of, and changes in the use of. formal (paid) and informal care by elderly persons who are chronically disabled and living in the community was studied. METHODS: Estimates were made of the sources and volume of home care use for persons reporting chronic disability in the 1982, 1989, and 1994 National Long Term Care Surveys. Comparisons were made across disability intensity, survey data, and age. RESULTS: The analyses showed changes over time in the sources of home care services. Generally, the combined use of both paid and informal home health care increased, whereas the use of either source of care alone decreased. The amount spent on formal care increased with disability level and age. DISCUSSION: Use of formal sources of care by community disabled elderly residents increased, likely because of changes in the Medicare home health care benefits in 1989. Increased use of home health care was associated with the concurrent use of informal care.

Activities of Daily Living↗
PubMed2000

Disability trends among elderly persons and implications for the future.

OBJECTIVES: This article used a new data source to examine the issue of disability trends among elderly persons and examined the potential implications of these trends on future health and long-term care needs. METHODS: We used the 1992-1996 Medicare Current Beneficiary Survey to examine time trends in rates of activities of daily living and instrumental activities of daily living disability and physical limitation among Medicare beneficiaries aged 65 and over. We used multinomial logit and least squares regression techniques to produce trend estimates that held the age, sex, race, and educational distributions constant and projected these trends into the future. Finally, we estimated the potential impact of disability decline on per capita Medicare spending on elderly persons. RESULTS: We found that disability among elderly persons is declining and that the trend toward a more educated elderly cohort explains some, but not all, of this decline. In the absence of downward disability trends, per capita Medicare expenditures would have grown even faster than they have. DISCUSSION: Although the decline in disability prevalence in recent years appears real, whether it continues has enormous implications for the size of the disabled population in the future and for the ability of the society to care for its disabled elderly members.

Activities of Daily Living↗
PubMed2000

A putative stimulatory role of progesterone acting via progesterone receptors in the steroidogenic cells of the human corpus luteum.

To further explore the proposed auto-regulatory role of progesterone action in the human corpus luteum (CL), the expression and functional roles of progesterone receptor (PR) isoforms A and B during the luteal phase (LP) of the menstrual cycle were investigated. A total of 27 otherwise healthy patients previously scheduled for surgery were recruited after informed consent. An LH rise was detected, and CL were grouped according to age (Days 2-5 post-LH-rise, early LP; Days 6-10, mid LP; Days 11-14, late LP). Using a semiquantitative reverse transcription-polymerase chain reaction assay, the PR-B mRNA levels, which were 100- to 1000-fold lower than PR-A/B mRNA, were 46% lower (P < 0.05, n = 24) in mid LP, compared to early and late LP. CL tissue levels of progesterone and PR-A/B protein levels were inversely correlated to increasing CL age; i.e., significantly reduced levels were observed in the late LP (r(2) = 0.34, P < 0.01, n = 23). Expression of PR-A/B mRNA as well as PR-A/B protein were detected by in situ hybridization and immunohistochemistry, respectively. Both methods revealed a clear and distinct localization to cells in the steroidogenic layer of the CL. Freshly obtained mid-luteal CL cells were cultured in vitro, and media were analyzed for progesterone concentrations after treatment by incremental doses of hCG and the stable PR antagonist mifepristone, alone or in combination. Mifepristone did not per se alter progesterone synthesis, but when it was added in conjunction with hCG, a dose-related inhibitory response was seen, with a maximal 47% reduction in progesterone output at a 10 microM addition (P < 0.05, n = 3). Collectively, these data implicate a stimulatory role of progesterone receptor-mediated action in the steroidogenic cells of the human CL, which may serve as an important pathway for maintaining functional homeostasis during early pregnancy.

Adult↗
PubMed2000

Inward potassium channel in guard cells as a target for polyamine regulation of stomatal movements.

A number of studies show that environmental stress conditions such as drought, high salt, and air pollutants increase polyamine levels in plant cells. However, little is understood about the physiological function of elevated polyamine levels. We report here that polyamines regulate the voltage-dependent inward K(+) channel in the plasma membrane of guard cells and modulate stomatal aperture, a plant "sensor" to environmental changes. All natural polyamines, including spermidine, spermine, cadaverine, and putrescine, strongly inhibited opening and induced closure of stomata. Whole-cell patch-clamp analysis showed that intracellular application of polyamines inhibited the inward K(+) current across the plasma membrane of guard cells. Single-channel recording analysis indicated that polyamine regulation of the K(+) channel requires unknown cytoplasmic factors. In an effort to identify the target channel at the molecular level, we found that spermidine inhibited the inward K(+) current carried by KAT1 channel that was functionally expressed in a plant cell model. These findings suggest that polyamines target KAT1-like inward K(+) channels in guard cells and modulate stomatal movements, providing a link between stress conditions, polyamine levels, and stomatal regulation.

Adaptation, Physiological↗
PubMed2000

Crystallization and preliminary crystallographic study of triple-helical DNA.

Single crystals of d(CTCCT(S)CCGCGCG).d(CGCGCGGAG) have been grown by the vapor-diffusion method using 2-methyl-2,4-pentanediol as a precipitant. The crystals are tetragonal, space group P4(2), with unit-cell parameters a = b = 53.8, c = 43.1 A, and diffract to 1.8 A resolution at a synchrotron X-ray beamline. In the crystal, the asymmetric unit contains one copy of the construct. The two halves of the structure are related by non-crystallographic twofold symmetry. These observations are consistent with the conclusion that the sequences of the 12-mer and 9-mer oligonucleotides form a duplex DNA at one end and a triplex DNA at the other end.

Base Sequence↗
PubMed2000

Elucidating the essential role of the A14 phosphoprotein in vaccinia virus morphogenesis: construction and characterization of a tetracycline-inducible recombinant.

We have previously reported the construction and characterization of vindH1, an inducible recombinant in which expression of the vaccinia virus H1 phosphatase is regulated experimentally by IPTG (isopropyl-beta-D-thiogalactopyranoside) (35). In the absence of H1 expression, the transcriptional competence and infectivity of nascent virions are severely compromised. We have sought to identify H1 substrates by characterizing proteins that are hyperphosphorylated in H1-deficient virions. Here, we demonstrate that the A14 protein, a component of the virion membrane, is indeed an H1 phosphatase substrate in vivo and in vitro. A14 is hyperphosphorylated on serine residues in the absence of H1 expression. To enable a genetic analysis of A14's function during the viral life cycle, we have adopted the regulatory components of the tetracycline (TET) operon and created new reagents for the construction of TET-inducible vaccinia virus recombinants. In the context of a virus expressing the TET repressor (tetR), insertion of the TET operator between the transcriptional and translational start sites of a late viral gene enables its expression to be tightly regulated by TET. We constructed a TET-inducible recombinant for the A14 gene, vindA14. In the absence of TET, vindA14 fails to form plaques and the 24-h yield of infectious progeny is reduced by 3 orders of magnitude. The infection arrests early during viral morphogenesis, with the accumulation of large numbers of vesicles and the appearance of "empty" crescents that appear to adhere only loosely to virosomes. This phenotype corresponds closely to that observed for an IPTG-inducible A14 recombinant whose construction and characterization were reported while our work was ongoing (47). The consistency in the phenotypes seen for the IPTG- and TET-inducible recombinants confirms the efficacy of the TET-inducible system and reinforces the value of having a second, independent system available for generating inducible recombinants.

Amino Acid Sequence↗
PubMed2000

Common polymorphism in promoter of microsomal triglyceride transfer protein gene influences cholesterol, ApoB, and triglyceride levels in young african american men: results from the coronary artery risk development in young adults (CARDIA) study.

The microsomal triglyceride transfer protein (MTP) plays a key role in the assembly of apolipoprotein B (apoB)-containing lipoproteins. We investigated the relation between lipid profiles and a common functional polymorphism (-493G/T) of the MTP gene in a large sample of young black men in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. We performed serial cross-sectional analyses on lipids of 586 black men in 5 exams over 10 years of follow-up. Total cholesterol, LDL cholesterol, and apoB levels were very similar between the GT and GG genotypes; therefore, the GT and GG genotypes were combined as 1 group when the 3 phenotypes were analyzed. The results from ANCOVA showed that the TT group (prevalence 7%) had higher levels of apoB-related lipids than did the GT+GG group: the difference in total cholesterol ranged from 2 (P=0.79) to 19 (P=0.002) mg/dL in exams 1 to 5; the difference in LDL cholesterol ranged from 10 (P=0.14) to 17 (P=0.003) mg/dL in exams 1 to 4, but in examination 5, the difference became negligible. The TT group had higher levels of apoB, measured in only 2 exams, by 6 (P=0.12) and 9 (P=0.03) mg/dL. The TT group had higher levels of triglycerides than did the TG or GG group by 3 to 34 (P=0.02 to approximately 0.003) mg/dL in all 5 exams. HDL cholesterol and apolipoprotein A-I levels were similar among the 3 genotypes. Our serial cross-sectional analyses indicated that the TT genotype was associated with higher levels of total cholesterol, LDL cholesterol, triglycerides, and apoB in young black men. The broad effect of this polymorphism on several atherogenic traits suggests that the MTP gene could be influential in atherosclerosis.

Adolescent↗
PubMed2000

Measuring physical activity in peripheral arterial disease: a comparison of two physical activity questionnaires with an accelerometer.

Peripheral arterial disease (PAD)-related exertional leg pain may limit physical activity, thereby contributing to mobility loss and increasing cardiovascular morbidity and mortality in men and women with PAD. The objectives of this study were: (1) to compare objectively measured physical activity levels between patients with and without PAD, (2) to assess the validity of two physical activity questionnaires in patients with PAD. Twenty PAD patients from a noninvasive vascular laboratory and 21 patients without PAD from a general medicine practice wore an accelerometer continuously for 7 days to measure physical activity objectively. After 7 days, participants completed the leisure time physical activity questionnaire (LTPAQ), derived from the Health Interview Survey, (continued on next page)and the Stanford 7-day physical activity recall questionnaire (PARQ). PAD participants had markedly lower physical activity levels than non-PAD participants as measured by accelerometer (803 kcal/week +/-364 (range=284-2,000, median=708) vs 1,750 kcal/week +/-1,296 (range=882-6,586, median=1,278), p<0.001). For the LTPAQ, physical activity levels in PAD and non-PAD participants were 609 kcal/week +/-576 (range=0-2,085, median=529) vs 832 kcal/week +/-784 (range=53-2,820, median= 623), p=0.128. For the PARQ, physical activity levels in PAD and non-PAD participants were 234 METS/week +/-21 (range=214-301, median=229) vs 238 METS/week +/- 11 (range=225-268, median=234), p=0.454, respectively. Pearson's correlation coefficient for the association between the accelerometer and the log-transformed LTPAQ measure was 0.419 (p=0.006). Pearson's correlation coefficient was 0.348 for the association between the accelerometer and the log-transformed PARQ measure of physical activity (p=0.026). In conclusion, PAD patients have significantly lower physical activity levels than non-PAD patients. Two commonly used physical activity questionnaires were less sensitive than objective measurement to the association between PAD and inactivity.

Aged↗
PubMed2000

Mucoepidermoid carcinoma arising in the glans penis.

Mixed carcinoma (squamous and glandular) of the penis is a rare neoplasm with an unknown origin and a poorly defined prognosis. The mucoepidermoid carcinoma described herein has not been previously reported to our knowledge. The present carcinoma arose from and extensively ulcerated the squamous epithelium of the glans penis, including that surrounding the urethral meatus. The neoplasm was composed of well-differentiated nonkeratinizing squamous cell carcinoma associated with large areas of carcinoma formed by cell nests that contained poorly differentiated squamous elements and large eosinophilic to pale granular cells. Mucin stains revealed approximately one quarter of the pale cells contained mucous substances. These findings are virtually identical to the mucoepidermoid type of carcinoma seen in the cervix. The 3 previously reported cases of adenosquamous carcinoma of the penis demonstrated a relatively indolent course, with only one being associated with a single inguinal lymph node metastasis. That patient was alive and well 9 years following diagnosis. Our example of mucoepidermoid carcinoma appears to demonstrate a more aggressive course than those reported previously.

Carcinoma, Mucoepidermoid↗
PubMed2000

Uterine smooth muscle tumors: utility of classification by proliferation, ploidy, and prognostic markers versus traditional histopathology.

CONTEXT: Accurate categorization of uterine smooth muscle neoplasms by light microscopic examination is difficult. Multiple classification schemes have been proposed based on mitotic rate, nuclear atypia, and the presence or absence of necrosis. None of these classification systems has been entirely successful. Multiple ancillary techniques have been tested for their ability to predict behavior of uterine smooth muscle tumors. OBJECTIVE: We assayed 45 smooth muscle neoplasms for a variety of proliferation markers, oncogene protein products, and DNA ploidy level to determine if these markers supplied prognostically useful information over and above that obtained by routine light microscopic assessment. STUDY DESIGN: Forty-five uterine smooth muscle neoplasms were assessed for DNA ploidy; silver-staining nucleolar organizer regions (AgNORs); percent nuclear proliferating cell nuclear antigen (PCNA); expression of p53, Her-2/neu, and MDM-2 protein; mitotic rate; and nuclear grade. These markers were correlated with histologic diagnosis and the occurrence of a clinically adverse event (death, metastasis, or recurrence). RESULTS: Diagnostic category (P <.001), nuclear grade (P <.002), mitotic activity (P <.001), mean AgNORs (P <.001), percent nuclear PCNA (P =.02), and expression of p53 (P =.02) all correlated with clinical outcome. No statistically significant correlation between clinical outcome and the categories MDM-2 expression, Her-2/neu expression, or DNA ploidy was seen. Nuclear grade, p53 expression, mitotic rate, AgNORs, and percent nuclear PCNA correlated with diagnosis. CONCLUSIONS: Diagnostic category, mitotic rate, AgNOR counts, PCNA, and p53 expression dichotomized uterine smooth muscle neoplasms into prognostically favorable and unfavorable groups. Although highly significant, the category AgNORs was no more successful than mitotic rate in dividing uterine smooth muscle neoplasms into prognostically favorable and unfavorable groups. Expression of p53 and percent nuclear PCNA dichotomized uterine smooth muscle neoplasms into prognostic groups, but neither technique reached the level of significance achieved by mitotic rate. Our data indicate that mitotic rate and the classification system of Kempson and Bari are at least as effective as the tested markers in separating uterine smooth muscle neoplasms into prognostic categories.

Aneuploidy↗
PubMed2000

Malignant giant cell tumor of synovium (malignant pigmented villonodular synovitis).

CONTEXT: Pigmented villonodular synovitis (PVNS) is a well-recognized entity that has the potential for extensive local destruction, even though it rarely metastasizes. Rare reports of malignant forms are recorded in the literature. We observed 2 patients in whom examples of PVNS followed an aggressive course with multiple recurrences, metastasis, or degeneration to an appearance resembling malignant fibrous histiocytoma. OBJECTIVE: We studied the occurrence and persistence of aneuploidy for chromosomes 5 and 7 in 2 patients with clinically aggressive PVNS. DESIGN: Fluorescence in situ hybridization was performed for the detection of chromosomes 5 and 7 in the primary lesions, recurrences, and metastases in 2 examples of PVNS. RESULTS: Fluorescence in situ hybridization demonstrated small but significant numbers of cells with trisomies for chromosomes 7 and/or 5 in both the primary and recurrent lesions of both patients. CONCLUSIONS: The presence of consistent chromosomal trisomies (5 and 7) in both patients' examples of PVNS suggests a neoplastic nature for this lesion. The persistence of these trisomies in the primary lesions, recurrences, and metastases supports a molecular link between the primaries, recurrences, and metastases despite changes in morphologic features. The presence of persistent trisomies in the recurrent and metastatic lesions supports the concept of malignant PVNS.

Adult↗
PubMed2000

Lack of association between the -308 polymorphism of the tumor necrosis factor-alpha gene and the insulin resistance syndrome.

BACKGROUND: Previous studies have demonstrated a role for tumor necrosis factor-alpha (TNF-alpha) in insulin resistance. A polymorphic variant of the TNF-alpha gene, the TNF2 allele, which is a guanine to adenine polymorphism at position -308 in the TNF-alpha promoter, is associated with higher basal and inducible promoter activity. The present study examined whether the TNF2 allele was associated with altered levels of different components of the insulin resistance syndrome, clustering of these components, or the 10-year change in the level of these components. METHODS: Components of the insulin resistance syndrome included insulin resistance, as determined by fasting insulin levels, body mass index, systolic blood pressure, triglycerides, uric acid, and high density lipoprotein-cholesterol. The study population was a subsample of participants from the Coronary Artery Risk Development in (Young) Adults (CARDIA) study, which included African American and white men and women aged 18-30. The sample included 243 black women, 142 black men, 392 white women, and 386 white men. Subjects were typed at the TNF-alpha locus. RESULTS: The frequency of the TNF2 allele was 12% in blacks and 16% in whites. Age-adjusted levels of the different components examined were not different at either baseline or year 10 in carriers of the TNF2 allele versus homozygotes for the wild-type allele, and the 10-year change in the level of different components was not different between the two genotype groups. There also was no evidence of increased clustering of components of the insulin resistance syndrome in carriers of the TNF2 allele. Moreover, there was no evidence of an association between the TNF2 allele and clustering across quartiles of BMI or quartiles of dietary fat intake (i.e., Key's score). CONCLUSIONS: In African Americans and whites, neither the TNF2 allele nor another polymorphism in the TNF-alpha gene or a neighboring gene with which the TNF2 allele is in linkage disequilibrium is associated with differences in the level of or increased clustering of components of the insulin resistance syndrome.

Adolescent↗
PubMed2000

Successful management of massive blood loss to extremely low hemoglobin in an elderly woman receiving spinal surgery.

Blood transfusion is absolutely indicated in acute anemia when the hemoglobin concentration falls below 6 g/dL. Sometimes it challenges the anesthesiologists if the blood intended for urgent transfusion is not readily or quickly available. In this case report, we describe an 81-year-old lady who accidentally sustained acute anemia after spinal surgery with the hemoglobin concentration falling to 1.4 g/dL. During the long wait for the process of cross-matching tests and delivery of blood from the blood bank in the city remote from the hospital, we could do nothing but administer crystalloid and colloid solutions to maintain the circulatory volume to prevent low cardiac output. Epinephrine was given when systolic blood pressure fell below 70 mmHg. Central venous pressure and arterial blood pressure were monitored to guide all the treatment. Fortunately, patient fully recovered on postoperative day 3 without any adverse events.

Aged↗
PubMed2000

[Construction of B. thuringiensis shuttle vector and expression of the cry1C gene].

We have constructed the E. coli-Bt shuttle vector pHV-1 by cloning the replicon (approximately 1.6 kb) of Bt ken-Ag and the aphI gene of pUC4K into pUC19. The rate of plasmid maintenance is more than 80% after 100 generations in E. coli, whereas 80% after 40 generations in Bti 4Q8. We have also constructed pHV-cry1C through cloning the alpha-amylase promoter from B. licheniformis and the cry1C gene from Bt 9510 into pHV-1 and introduced it into Bti 4Q8 by means of electroporation. Under the microscope, we can see that there is no crystal in Bti 4Q8, however, there are many rhomboid crystals in Bti 4Q8 (pHV-cry1C), which are smaller than those of Bt 9510. The bioassay result of Bti 4Q8 (pHV-cry1C) demonstrates that the expressed crystal protein is insecticidally active against Spodoptera exigue.

Animals↗
PubMed2000

Coronary artery bypass grafting on the beating heart using the octopus method--a case report.

A 74-year-old male was admitted due to chest tightness for one month. He had received percutaneous transilluminal coronary angioplasty (PTCA) because of single-vessel disease one year ago. Cardiac catheterization examination carried out during this admission revealed 90% stenosis of the left anterior descending coronary artery (LAD) and circumflex branch (CX). Because another attempt of PTCA was considered not optimal, the patient was advised to undergo surgical grafting to which he consented. After expediently balancing the merits and demerits of every practicable surgical procedure--the essential determinant in selection of which was that the patient's condition and criteria of indication of that procedure were in perfect harmony--we decided to carry out minimally invasive direct coronary artery bypass (MIDCAB) with the application of Octopus tissue stabilizer. We report the surgical course and anesthetic management of the patient and discourse some detail in MIDCAB.

Aged↗