Fibre-type X-ray diffraction patterns from single crystals of triple helical DNA.
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Base Sequence↗
Biomedical subjects
K Liu
Publications and source records attributed to K Liu.
Statistical issues related to semiquantitative food-frequency questionnaires.
Semiquantitative food-frequency (SQFF) questionnaires have been used by many epidemiological studies to collect dietary data. These methods are especially attractive for use in large-scale studies because they are often self-administered and/or completed with minimal time or effort. This paper discusses several statistical issues related to the use of dietary data collected by frequency methods. In particular, the paper addresses 1) whether SQFF methods are well-validated dietary methods as suggested by many investigators and 2) whether data based on SQFF methods can be used to compare mean dietary intakes among different populations and to estimate the distribution of usual nutrient intakes in a national probability population. Data from several validation studies are used to evaluate the impact on statistical analyses of measurement error associated with certain SQFF methods. These examples help to illustrate the potential problems and clarify the interpretation of the results. In addition, concerns about the misuse of dietary data derived from SQFF questionnaires are also discussed.
Diet Surveys↗
Reaction of Cr(VI) with ascorbate and hydrogen peroxide generates hydroxyl radicals and causes DNA damage: role of a Cr(IV)-mediated Fenton-like reaction.
Incubation of Cr(VI) with ascorbate generated Cr(V), Cr(IV) and ascorbate-derived carbon-centered alkyl radicals, as well as formyl radicals. H2O2 caused generation of hydroxyl radicals (OH) and much higher levels of Cr(V), showing that .OH can be generated via a Cr(IV)-mediated Fenton-like reaction (Cr(IV) + H2O2-->Cr(V) + .OH + OH-). 1,10-Phenanthroline and deferoxamine inhibited the formation of both .OH and Cr(V) from the reaction of Cr(VI) with ascorbate in the presence of H2O2. Electrophoretic assays showed that ascorbate-derived free radicals caused DNA double-strand breaks. .OH radicals generated by Cr(V)- and Cr(IV)-mediated Fenton-like reactions also caused DNA double-strand breaks. HPLC measurements showed that .OH radicals generated by Cr(IV) and Cr(V) from H2O2 caused 2'-deoxyguanine hydroxylation to form 8-hydroxy-2'-deoxyguanine.
8-Hydroxy-2'-Deoxyguanosine↗
A data perspective on long-term care.
Continuing progress in developing empirical information on different facets of long-term care service use has been possible because of improvements in the design of data sets. New generations of data sets are being developed with a recognition of the inherent nature of long-term care. Notably, long-term care implies care received over an extended period of time, thereby presenting numerous occasions for changes in the characteristics of both the services that are used and the recipients of the services. In large part, the design of the data sets has been made in response to research and policy interests in long-term care. This article highlights some observations about progress in the development of long-term care data, and the relationship between policy questions in long-term care and the design of relevant data sets.
Aged↗
Risk of entering nursing homes for long versus short stays.
Research on the risk of nursing home use has generally not distinguished between risk for long versus short stays. This paper presents an analysis of data from the 1982-84 National Long-Term Care Surveys to identify characteristics of disabled persons that predicted one or the other type of stay. Measures that are recognized to be strong predictors of nursing home use in general, such as dependencies in activities of daily living and cognitive impairment, were not significantly associated with admission for short stays. Results from the multivariate analysis were also used to make projections of lifetime risk of long and short stays. Approximately one-third of lifetime nursing home risk applies to stays of 90 days or less.
Activities of Daily Living↗
Primary non-Hodgkin's lymphoma of the intestine: a morphological, immunohistochemical and clinical study of 31 Chinese cases.
Thirty-one cases of primary non-Hodgkin's lymphoma of the intestine were investigated. Twenty-one were of B-cell and 10 of T-cell origin. The B-cell lymphomas comprised two cases of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT), one of centroblastic/centrocytic type, three of high-grade B-cell lymphoma coexisting with a low-grade B-cell lymphoma of MALT, nine of centroblastic, three of immunoblastic and three of Burkitt type. Of the T-cell lymphomas, eight were of pleomorphic medium-to large-sized cell type and two of large cell anaplastic type. All the B-cell lymphomas expressed CD20 (L26) and/or Ki-B5; in six there was monotypic immunoglobulin light chain restriction. Membrane positivity for CD45RO (UCHL1) was observed in the 10 cases of T-cell lymphoma, but the tumour cells did not express monocyte-macrophage markers. Clinically, the patients with T-cell lymphomas were usually young males with constitutional symptoms and their prognosis was significantly worse than those of patients with intestinal B-cell lymphoma.
Adolescent↗
Ectopic vasal insertion into the posterior urethra.
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Humans↗
Hemostatic factors in the Coronary Artery Risk Development in Young Adults (CARDIA) Study.
Elevated levels of factor VII (FVII) and fibrinogen (Fb) have been reported as risk factors for coronary heart disease in middle-aged and older adults. The purpose of this study was to determine whether increased levels of these and other hemostatic factors (FVIII, von Willebrand factor [vWF]) were associated with other coronary risk factors in young adults participating in the Coronary Artery Risk Development in Young Adults (CARDIA) Study. Hemostatic factors were measured in 1724 participants aged 23 to 35 years who were roughly balanced by sex and race (black/white). Fb was greater in women than men (black, 288 versus 253 mg/dL; white, 267 versus 240 mg/dL; overall P < .05 by Scheffé multiple-comparison test), and FVIII and vWF were higher in blacks than in whites (FVIII in men, 103% versus 88%, and in women, 104% versus 91%; vWF in men, 114% versus 98%, and in women, 117% versus 99%; P < .05). The latter factors were lower in those with blood group O, but within each blood group (except group A), blacks had significantly higher levels of FVIII and vWF. Fb was positively correlated with body mass index (r = .27 to .48, P < .001), total cholesterol (r = .13 to .17, P < .05), and low-density lipoprotein cholesterol (r = .15 to .22, P < .01) in all groups and with blood pressure, triglycerides, and cigarette smoking in white men. FVII correlated positively with cholesterol (r = .12 to .29, P < .05) and triglycerides (r = .23 to .32, P < .001) in all groups and with low-density lipoprotein in whites.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Effect of subglottic pressure on fundamental frequency of the canine larynx with active muscle tensions.
The relation between subglottic pressure and the fundamental frequency of vocal fold vibration was studied by means of evoked phonation in an in vivo canine model. The evoked-phonation model involved electrical stimulation of the midbrain that resulted in consistent responses by respiratory and laryngeal musculature, accompanied by phonation. The dynamic stiffness properties of the vocal folds, especially the "cover," were investigated by delivering various amounts of air pressure to the larynx from an opening in the trachea. The fundamental frequency of vocal fold vibration increased linearly with subglottic pressure. The slopes ranged from 22.4 to 118.7 Hz per kilopascal in 7 animals. The results indicated that the dependence of fundamental frequency on subglottic pressure is a passive mechanical phenomenon.
Animals↗
Pericardiocentesis and drainage by a silicon rubber line without echocardiographic guidance. Experience in 55 consecutive patients.
Pericardiocentesis and drainage with a silicon rubber line were performed safely in 55 patients via the subxiphoid (80 times) or apical (1 time) approach at the bedside without echocardiographic guidance. The subxiphoid approach, which is close to the posterior of the sternum or the costal cartilage with a small acute-angle (15-30 degrees) to the parietal pericardium in front of the right ventricle, can avoid injuring the heart, liver and lungs. A line with sideholes near the distal end, which provides convenient drainage and has better histocompatibility, can be kept in place for a long period of time (1-82 days). It was also convenient to inject air, drugs or fluid through the line. There were no procedure-related serious complications or deaths. Emergency drainage with the Seldinger technique, especially for small to moderate effusions, is safe and simple.
Catheters, Indwelling↗
Creating a MEDPAR (Medicare provider analysis and review) analog to the RUG-III (Resource Utilization Groups, Version III) classification system.
As Medicare payments for post-acute institutional care continue to rise sharply, policy interest in the clinical characteristics of beneficiaries admitted to nursing homes and their variation across facilities has stimulated research into case mix. Measures of Medicare skilled nursing facility (SNF) case mix are important in relating payments to the care requirements of residents. The Resource Utilization Groups, Version III (RUG-III) classification system uses a new minimum data set that is not currently available nationally. In preparation for a multi-State demonstration, we needed to simulate at least the first-level splits at the national, State, and facility level. Therefore, we developed proxy measures using comparable data available on the National Claims History files. The analog is an easily programmed measure of the acuity/severity of beneficiaries' conditions across a Medicare Part A SNF stay in 75 percent of the SNF providers. This can be a method for estimating changes in case mix over the years, and differences across provider types and States.
Activities of Daily Living↗
[Clinical analysis and treatment of 68 spaced dentition cases]
One of the characteristic feature of normal occlusion is arch continuity, as expressed by proximal contact between all teeth in each dental arch.The dental arches of a consider able number of individuals show space between some,or even all,of the teeth.Such dental arches are know as spaced dentition.It is detrimental of arch integrity, esthetics and normal dental function.The purpose of this article to study distribution according to sex and age,number and location of the spaces,their etiology and principle of orthodontic treatment.In a random sample of 68 cases of the participating patients who is space greater than 0.5 millimeter between the proximal surface of adjacent teeth.The samples were divided into three age groups, the exact width of each space was measured by calipers in table.
Journal Article↗
A study of the reliability and comparative validity of the cardia dietary history.
This study evaluated the reliability and comparative validity of the dietary history survey method developed for CARDIA, a longitudinal investigation of life-styles and the evolution of cardiovascular risk factors in young adults. The method was tested in a sample of 30 white men, 33 white women, 33 black men, and 32 black women, aged 18 to 35 years, in four regions reflecting the race, sex, age, and geographical distribution of CARDIA participants. For 64 of the participants, two dietary history interviews, 1 month apart, were conducted by trained nutritionists. These data were used to examine the reliability of the method. For all participants, seven telephone- assessed 24-hour dietary recalls were randomly scheduled during a 28-day period and were followed by a dietary history interview. These data were used to examine the comparative validity of the method. Calories, total fat, saturated fat, polyunsaturated fat, monounsaturated fat, dietary cholesterol, protein, carbohydrate, alcohol, potassium, calcium, and vitamin A were selected by the CARDIA Nutrition Working Group as the nutrients for comparison. Mean nutrient values from the first history tended to be higher than those obtained from the last history. However, for a majority of the nutrients, the differences were significant for blacks but not for whites. The correlations for the log-transformed nutrient values and calorie-adjusted nutrient values from the two histories were generally in the range of 0.50 to 0.80 for whites. For blacks, the correlations were lower, with a majority in the range of 0.30 to 0.70. The average nutrient values estimated from the histories were higher than those estimated from the average of the seven 24-hour recalls. The differences in blacks were larger than in whites. For both the log-transformed nutrient values and the calorie-adjusted nutrient values, the correlations between the two methods were generally larger than 0.50 for whites. However, for blacks, the correlations were lower, and for several macronutrients, the correlations were close to zero. These results suggest that the CARDIA dietary history is a reasonably reliable and valid dietary survey method for obtaining information about habitual intakes in whites. In blacks, the results are less consistent. The black-white differences remained when the analyses were stratified by education. These results raise a question about differences in reporting between blacks and whites.
Adolescent↗
Coordinated regulation of tissue type plasminogen activator and plasminogen activator inhibitor type-1 gene expression in hypophysectomized rat ovaries during GnRHa-induced ovulation.
In this study we have demonstrated that both granulosa and theca-interstitial cells of hypophysectomized rat ovaries are capable of synthesizing tPA and PAI-1. Injection of a GnRH agonist can markedly induce these gene expressions in the ovary in a cell-specific and time-coordinated manner, so that a surge of tPA mRNA and its activity in both granulosa and theca-interstitial cells was obtained just prior to ovulation. Theca-interstitial cells make PAI-1 become the most active in the ovary. Both the amount PAI-1 mRNA and its activity in the cells reach the maximum level 6 h before the tPA peak. By contrast, granulosa cells produce only a little amount of PAI-1 (most increase tPA activity), and both PAI-1 mRNA and activity in the cells reach the maximum after ovulation. The coordinated regulation of tPA and PAI-1 in the ovary may fine-tune the peak of tPA activity which may be important for the regulation of the ovulatory process. The changes of tPA and PAI-1 in the ovarian cells of hypophysectomized rats during GnRHa-induced ovulation are similar to that in intact rats during hCG-induced ovulation, suggesting that the ovulatory process can be modulated by different regulatory signals mediated by influencing the coordinated expression of both tPA and PAI-1.
Animals↗
Institution of a pediatric liver transplantation program with living-related orthotopic liver transplantation: initial experience in Hong Kong.
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Adult↗
Liver infested with Clonorchis sinensis in orthotopic liver transplantation: a case report.
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Animals↗
Hormonal regulation of expression of tissue type plasminogen activator and plasminogen activator inhibitor type 1 in cultured rat granulosa cells.
In the present study, gonadotropin and gonadotropin-releasing hormone (GnRH) regulation of tPA and PAI-1 expression in PMSG-primed granulosa cells has been investigated. (i) Addition of gonadotropins (FSH and LH) and GnRH agonist (GnRHa) or PMA to the culture increases tPA activity; FSH (or LH) plus GnRHa (or PMA) in the culture further enhances the enzyme production to such an extent that a more obvious effect than the additive effect caused by these hormones used alone has been observed; (ii) in contrast, FSH and LH decrease PAI-1 activity, whereas GnRHa and PMA alone markedly increase PAI-1 mRNA level and PAI-1 activity. Because FSH and LH stimulate tPA production and have no significant effect on PAI-1 mRNA induction, the observed inhibition of PAI-1 activity by gonadotropins may be due to the occurrence of neutralization of PA and PAI-1 proteins in the conditioned media by the formation of complexes between PA and PAI-1; (iii) increases in PAI-1 mRNA level and activity by GnRH and PMA are completely inhibited by the co-addition of FSH or LH to the culture. It is, therefore, suggested that the mechanism of gonadotropin and GnRHa regulation of tPA and PAI-1 expression in granulosa cells is different.
Animals↗
Plasma fibrinogen: levels and correlates in young adults. The Coronary Artery Risk Development in Young Adults (CARDIA) Study.
Sufficient evidence exists that plasma fibrinogen is a risk factor for cardiovascular disease to prompt a search for fibrinogen determinants. The authors measured fibrinogen in 4,193 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study with three objectives: to describe fibrinogen levels in young adults, to determine if correlates of fibrinogen in older adults apply to younger adults, and to examine several additional hypothesized correlates. Fibrinogen (overall mean +/- standard deviation = 263 +/- 57 mg/dl) was greater in women than in men and in blacks than in whites; it was associated positively with cigarette smoking, body mass index, low density lipoprotein cholesterol, triglycerides, and blood pressure, and negatively with physical activity, high density lipoprotein cholesterol, and ethanol intake. Socioeconomic stress indicators and negative personality traits hypothesized as being associated with fibrinogen, possibly through adrenergic mechanisms, proved weak correlates. Parental history of diabetes was correlated positively with fibrinogen, in part because those with a positive parental history had greater body mass. Diabetes mellitus, lipoprotein(a), left ventricular mass, and oral contraceptive use were also positively correlated with fibrinogen concentration. Thus, even in young adults, fibrinogen is associated positively with most risk factors for atherosclerotic cardiovascular disease. This has implications for the role of fibrinogen as a risk factor and, potentially, for cardiovascular disease prevention.
Adolescent↗