Local-density approximation, hierarchy of equations, functional expansion, and adiabatic connection in current-density-functional theory.
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Journal Article↗
Biomedical subjects
S Liu
Publications and source records attributed to S Liu.
Expansions of the pair distribution function and the second-order density matrix in terms of homogeneous functionals.
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Journal Article↗
The potential role of gastroesophageal reflux in the pathogenesis of food-induced wheezing.
Severe reactive airways disease (RAD) in children is frequently associated with gastroesophageal reflux or food allergy. However a relationship between these two confounding factors has yet to be investigated. We postulate that, in certain patients with micro-aspiration of gastric contents into the airways, food allergens sensitize T cells in the peribronchial lymphoid tissue and induce the production of food-specific IgE antibodies that sensitize airway cells. Subsequent exposure to these food allergens might then induce IgE dependent mediator release from mast cells as well as T cell and eosinophil activation, thus contributing to airway inflammation and RAD. In the current report, we describe the case of a patient with severe asthma who had food allergy and gastroesophageal reflux whose clinical findings support this hypothesis. We also provide additional evidence for a high rate of food sensitization in patients with bronchopulmonary dysplasia (BPD), RAD and GER. We conclude that additional studies are warranted to examine the possibility that patients who have RAD and GER require an evaluation for food allergy.
Adolescent↗
1,2-Dioctanoyl-sn-glycerol depresses cardiac L-type Ca2+ current: independent of protein kinase C activation.
The present study examines the effect of 1,2-dioctanoyl-sn-glycerol (DiC8), a diacylglycerol analogue, on L-type Ca2+ current (ICa,L) in adult rat ventricular myocytes using whole cell patch-clamp techniques. Extracellular application of DiC8 (1-10 microM) resulted in a concentration-dependent inhibition of peak ICa,L (half-maximum inhibitory concentration = 2.2 microM). Results obtained from the current-voltage relationship showed that DiC8 decreased the slope conductance. In addition, DiC8 increased the rate of Ba2+ current inactivation and caused a hyperpolarizing shift in the steady-state inactivation by 6 mV and a decrease in the slope factor. The DiC8-induced inhibition of ICa,L was neither mimicked by activation of protein kinase C (PKC) with 100 nM phorbol 12-myristate 13-acetate (PMA) no prevented by inhibition of PKC with 30 microM H-7, 100 nM staurosporine, or 24-h pretreatment with PMA. These results suggest that in rat ventricular myocytes 1) 1,2-sn-diacylglycerol (DAG) inhibits ICa,L, possibly by facilitating channel inactivation and decreasing channel availability and 2) this inhibitory effect of DAG is independent of PKC activation.
Animals↗
Whole cell potassium currents in fetal rat alveolar type II cells cultured on Matrigel matrix.
Patch-clamp studies were performed on fetal rat alveolar type II cells isolated at 19 days of gestation and cultured on either plastic for 7 days or Matrigel matrix (40-50 microliters/cm2) for 10 days. Before study, cells cultured on Matrigel matrix were dissociated from alveolar-like structures with enzymes, replated, and washed with cold buffer at a constant flow rate to remove residual gel. This wash significantly improved obtaining of successful seals. Potassium current-voltage relationships and maximum whole cell K+ conductance (normalized to membrane capacitance) were significantly changed with time in cells cultured on plastic, but no significant change occurred in cells cultured on Matrigel matrix. Application of 20 mM tetraet hyl ammonium, 2mM 4-aminopyridine, and 5mM BaCl2 significantly inhibited K+ currents, showing differences in channel sensitivity to these agents and a voltage-dependent blockage between culture groups or with time in culture. To conclude, we have developed a new method by which epithelial cells cultured on Matrigel matrix can be successfully studied with the use of patch-clamp techniques. Furthermore, these studies show that fetal type II cells have voltage-activated K+ channels and that channel density and their sensitivity to channel blockers are modulated by the substratum on which the cells are cultured.
Animals↗
Dietary fat modifies exercise-dependent glucose transport in skeletal muscle.
Exercise stimulates muscle glucose uptake both directly and by increasing the sensitivity of this process to insulin. This study was designed to investigate whether the level of dietary fat would interact with the action of acute exercise in the presence or absence of insulin. Weanling female Sprague-Dawley rats were fed two levels of dietary fat (5 vs. 20%; wt/wt) for 6 wk. Rats then remained sedentary or were exercised by a single bout of swimming for a total of 2 h with 5-min rest intervals each 0.5 h. Basal (insulin-independent) and insulin-stimulated glucose uptake rates were determined in isolated epitrochlearis muscles by using 3-O-[methyl-3H]methyl-D-glucose. Muscles of sedentary rats fed a high-fat diet showed decreased glucose uptake overall because of a marked decrease in insulin-stimulated uptake. Muscles of rats fed a high-fat diet also showed considerable impairment of insulin-dependent glucose uptake measured both immediately and 3.5 h after exercise. Glucose uptake was suppressed by 64% at half-maximal concentrations of insulin (0.8 nM) and by 34% at maximally stimulating (20 nM) insulin levels. This lowered sensitivity and response to insulin were not altered by acute exercise. Glucose uptake in response to acute exercise (insulin independent) was quantitatively similar in rats fed high- and low-fat diets; rats on high-fat diet, however, showed higher insulin-independent glucose uptake at 3.5 h after exercise.
Animals↗
In situ hybridization reveals extensive diversity of K+ channel mRNA in isolated ferret cardiac myocytes.
The molecular basis of K+ currents that generate repolarization in the heart is uncertain. In part, this reflects the similar functional properties different K+ channel clones display when heterologously expressed, in addition to the molecular diversity of the voltage-gated K+ channel family. To determine the identity, regional distribution, and cellular distribution of voltage-sensitive K+ channel mRNA subunits expressed in ferret heart, we used fluorescent labeled oligonucleotide probes to perform in situ hybridization studies on enzymatically isolated myocytes from the sinoatrial (SA) node, right and left atria, right and left ventricles, and interatrial and interventricular septa. The most widely distributed K+ channel transcripts in the ferret heart were Kv1.5 (present in 69.3% to 85.6% of myocytes tested, depending on the anatomic region from which myocytes were isolated) and Kv1.4 (46.1% to 93.7%), followed by kv1.2, Kv2.1, and Kv4.2. Surprisingly, many myocytes contain transcripts for Kv1.3, Kv2.2, Kv4.1, Kv5.1, and members of the Kv3 family. Kv1.1, Kv1.6, and Kv6.1, which were rarely expressed in working myocytes, were more commonly expressed in SA nodal cells. IRK was expressed in ventricular (84.3% to 92.8%) and atrial (52.4% to 64.0%) cells but was nearly absent (6.6%) in SA nodal cells; minK was most frequently expressed in SA nodal cells (33.7%) as opposed to working myocytes (10.3% to 29.3%). Two gene products implicated in long-QT syndrome, ERG and KvLQT1, were common in all anatomic regions (41.1% to 58.2% and 52.1% to 71.8%, respectively). These results show that the diversity of K+ channel mRNA in heart is greater than previously suspected and that the molecular basis of K+ channels may vary from cell to cell within distinct regions of the heart and also between major anatomic regions.
Animals↗
Assessment of a severe-weather warning system and disaster preparedness, Calhoun County, Alabama, 1994.
Tornado preparedness warning system effectiveness, and shelter-seeking behavior were examined in two Alabama areas after tornado warnings. In the area without sirens, only 28.9% of 194 respondents heard a tornado warning of these, 73.2% first received the warning from radios or television. In the area with sirens, 88.1% of 193 respondents heard a warning, and 61.8% first received the warning from a siren. Knowledge of warnings, access to shelter, and education were key predictors for seeking shelter. Our findings indicate that installing sirens, providing access to shelter, and teaching appropriate responses to warnings are important elements of an effective disaster prevention system.
Alabama↗
Cigarette smoking and its risk factors among elementary school students in Beijing.
OBJECTIVES: This study investigated patterns of and risk factors for smoking among elementary school children in Beijing, China. METHODS: In 1988, anonymous questionnaires were administered to a multistage stratified cluster sample of 16996 students, aged mostly 10 to 12, in 479 fourth- to sixth-grade classes from 122 Beijing elementary schools. RESULTS: Approximately 28% of boys and 3% of girls had smoked cigarettes. The most frequently cited reasons for smoking initiation were "to imitate others' behavior" and "to see what it was like." Girls were more likely to get cigarettes from home than to purchase their own. Having close friends who smoked and being encouraged by close friends to smoke were strong risk factors for smoking. Smoking was also associated with lower parental socioeconomic status; having parents, siblings, or teachers who smoked; buying cigarettes for parents; performing poorly in school; and not believing that smoking is harmful to health. CONCLUSIONS: Gender differences in smoking prevalence among adolescents in China are larger than those among US teenagers, whereas the proximal risk factors for smoking are similar. Major efforts are needed to monitor and prevent smoking initiation among Chinese adolescents, particularly girls.
Adolescent↗
A rapid HPLC method for the quantification of GSH and GSSG in ocular lens.
UNLABELLED: Purpose. To develop a rapid and accurate method for the quantification of reduced glutathione (GSH) and oxidized glutathione (GSSG) using micro-quantities of ocular lens. Methods. The epithelium, cortex and nucleus of the lens were separated and also the whole lens was homogenized in 3% metaphosphoric acid. The homogenate was ultrafiltered by centrifugation at 10,000 g in an Amicon microconcentrator, molecular weight cut off 3,000 g. The method does not require prior derivatization of the glutathiones. The filtrate was analyzed on a Microsorb-MV by a high performance liquid chromatography (HPLC) column using an isocratic solvent system (3% methanol and 10 mM potassium phosphate, pH 3.0) and detection at 200 nm. RESULTS: The GSH and GSSG were eluted from the HPLC column at retention times 5 and 10 min, respectively. The detection limit was 100 pmoles applied to the column. The recovery of GSH and GSSG added to the tissue samples was 97-100%. CONCLUSIONS: A fast and sensitive HPLC-method for the quantification of picomole quantities of GSH and GSSG in ocular lens, which does not require prior derivatization, has been developed.
Animals↗
[Formation and shifting of TCM center].
Analysis is made on the so-called "Yuasa Phenomenon" in the history of Chinese medicine, which holds that, in the development of medical history, there exists a center of medical theory and practice representing the peak of development and orientation. Since the Song-Yuan dynasties, there was a process of constant changes and formation of medical center. This period had seen three separate TCM centers in Henan, Hebei and South of Yangtze River, discerning four stages, viz., inheritance, invention, renewal and unprecedented flourishing. This is a phenomenon not only reflecting the internal laws of medical development, but also deeply embodying the profound influence of social economy and culture on medicine.
China↗
Specific and effective interaction of a guanine nucleotide analogue with small G proteins.
G proteins are molecular switches that use a cycle of GTP binding and hydrolysis to regulate a wide variety of cellular biochemical processes. Because the functional state of these proteins is allosterically determined by bound guanine nucleotides, a nucleotide analogue with protein specificity might have pharmacological or biochemical value. The binding of [alpha-32P]GTP to four small G proteins immobilized on nitrocellulose was competed by a series of analogues with modifications at multiple sites. One analogue, N2-(p-n-butylphenyl)guanosine 5'-(beta,gamma-difluoromethylene)triphosphate, had a approximately 40-fold higher affinity for one small G protein than for two of the others. Systematic analysis of each modification in the synthetic nucleotide revealed that specificity was conferred by the carbon substitution in the beta,gamma-phosphoanhydride bond. These observations were then extended to purified proteins of known sequence in solution by filtration binding studies with H-ras and rab5. Ras was 9-fold more discriminant between guanosine-5'-(beta,gamma-difluoromethylene)triphosphate and guanosine-5'-O-(3-thiotriphosphate) than was rab5, and the Q79L GTPase-defective mutant of rab5 was 6-fold more discriminant than wild-type rab5. Guanosine-5'-(beta,gamma-difluoromethylene)triphosphate protected a 20-kDa fragment of rab5 from tryptic proteolysis with greater efficacy than guanosine-5'-O-(3-thiotriphosphate) or guanosine-5'-(beta,gamma-imido)triphosphate despite its lower affinity, and GMP stabilized a conformation indistinguishable from apo-rab5. These results identify a synthetic guanine nucleotide analogue with differential affinity for closely related G proteins, determine the atomic substitution in the analogue that confers specificity, demonstrate discrimination by the analogue between wild-type and a point-mutant G protein, and establish efficacy of the analogue in inducing conformational change of a target protein disproportionate to the affinity of the interaction.
Amino Acid Sequence↗
[Expression of p53 in human esophageal carcinoma and pre-malignant lesions in the esophagus].
The levels of p53 protein were detected by immunocytochemistry in 197 endoscopic biopsy specimens of esophagus. Nuclear p53 protein was present in 2.9% of normal mucosa, 6.7% of inflammatory mucosa, 38.8% of mild dysplasia, 52.0% of moderate or severe dysplasia, 61.1% of carcinomas in situ, 62.5% of invasive carcinomas. Moreover, we examined 14 cases of esophageal carcinoma with extensive dysplasia near the carcinoma and found high levels of p53 protein in both dysplasias and carcinomas in 8 cases. In one case, carcinoma presented high level of p53 protein while the adjacent dysplasia did not. In another case, the result was just the opposite. Negativity for p53 immunostaining was found in 4 cases. These data indicated that p53 protein accumulation occurred before tumor invasion in the multistage esophageal carcinogenesis. The timing and the frequency of p53 protein accumulation made p53 gene an attractive marker for the early diagnosis an the evaluation of chemopreventive agents.
Carcinoma in Situ↗
[Study on ultrastructure morphology of fine needle aspiration of mediastinal and lung lesions].
Specimens of Mediastinal lesions and lung masses collected by fine needle aspiration (FNA) was examined with both light and transmission electron microscopy. Sixty eight specimens (9 mediastinal and 40 lung masses, 4 metastatic chest masses and 15 metastatic lymph nodes from lung cancer) from 104 cases (60.5%) were satisfactory for evaluation. With light microscopy, the nature of the lesions was assessed and the ultrastructural features of the lesions were evaluated with transmission electron microscopy. Diagnosis of histologic type of the lesions by light microscopy was consistent with that by transmission electron microscopy at a conformity rate of 50.4%. The results indicate that ultrastructural features are valuable in ascertaining histologic type of the lesions.
Adenocarcinoma↗
Radiation risks: threshold or no threshold. The centenary of the discovery of X-rays by W.C. Roentgen.
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Animals↗
Interaction of electron leak and proton leak in respiratory chain of mitochondria--proton leak induced by superoxide from an electron leak pathway of univalent reduction of oxygen.
By incubating the isolated rat myocardial mitochondria with xanthine-xanthine oxidase, an exogenous superoxide (O2.-) generating system, and by ischemia-reperfusion procedure of isolated rat heart as an endogenous O2.- generating system, it was found that both sources O2.- showed the same injurious effects on mitochondrial function resulting in (i) increasing proton leak rate, lowering proton pumping activity and H+/2e ratio of respiratory chain, and (ii) decreasing transmembrane potential of energized mitochondrial inner membrane by succinate oxidation. The injurious effects of O2.- on these mitochondrial bioenergitical parameters mentioned above exhibited a dosage- or reaction time-dependent mode. O2.- has no effects on the electron transfer activity and transmembrane potential of nonenergized mitochondria. Being a superoxide scavenger, 3,4-dihydroxylphenyl lactate showed obvious protection effects against damage of both exogenous superoxide sources from xanthine-xanthine oxidase system and endogenous O2.- source from ischemia-reperfused heart on proton pumping activity, H+/2e ratio and transmembrane potential of energized mitochondria. The experimental results presented here clearly showed that O2.- radicals induce an increase of proton leak in mitochondria directly related to the molecular mechanism of early phase damage of ischemia-reperfused heart, and also provide evidence to support our recent proposed hypothesis that electron leakage to oxygen to form O2.- in respiratory chain is one of the mechanical cause of proton leakage in mitochondria.
Animals↗
Investigation on inhibition of biological effects of endothelin.
The effects of a series of substances on the biological function of endothelin (ET) are reported. The substances used are: synthetic inhibitors of endothelium derived relaxing factors (EDRFs), inhibitor of big-endothelin converting enzyme phosphoramidon, antiserum of endothelin, antagonists of endothelin A receptor BQ123 and JKC301, and two Chinese anti-snake venom herb medicines Lobelia radicans Thumb and Taris polyphylla Smith var. chinensis (Franch) Hara. The results showed that inhibiting the production of nitric oxide (NO) could stimulate ET release from vascular endothelium, elevate plasma ET and increase blood pressure. These changes could be reversed by L-arginine (L-Arg), the substrate of nitric oxide synthase (NOS). The amount of ET released by arterial endothelium could be increased or inhibited by inhibiting or stimulating the synthesis of prostacyclin (PGI2). The plasma ET level and blood pressure in both SHR and WKY rats could be decreased by giving phosphoramidon (PhR). The above results indicate that the biological effects of ET could be antagonized by inhibiting the synthesis or release of ET, decreasing the level of plasma ET, blocking the binding of ET with its receptor and using some Chinese anti-snake venom herb medicines.
Animals↗
Lack of effect of calcium channel blockers on open-angle glaucoma.
PURPOSE: The objective of this study is to evaluate the effect of calcium channel blockers (CCB) on the clinical course of glaucoma. METHODS: Open-angle glaucoma patients receiving oral CCB for nonophthalmic diseases were sequentially selected from the private practice of the Glaucoma Service of Wills Eye Hospital. The course of visual fields and optic discs and serial intraocular pressures were analyzed in subsequent follow-ups. The findings in these 83 cases were compared with a control group of patients with the same ocular diagnosis, but who were not on CCB. A subset of 43 cases of the study group was compared with an age-matched subset of the control group. RESULTS: There was no apparent difference in the absolute intraocular pressure, stability/change of visual fields or optic discs when we compared patients using CCB with the control group. Among patients with the diagnosis of "low-tension glaucoma," we also could not demonstrate any statistically significant difference between the two groups. CONCLUSIONS: In this study, neither a beneficial nor a detrimental effect of CCB on the course of the patients glaucomatous disease was apparent.
Aged↗