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Biomedical subjects

X Sun

Publications and source records attributed to X Sun.

At least 415 records · Page 23Linked to original sources
PubMed1996

Applications of magnetic resonance imaging in food science.

The physical and chemical changes that occur in foods during growth, harvest, processing, storage, preparation, and consumption are often very difficult to measure and quantify. Magnetic resonance imaging (MRI) is a pioneering technology, originally developed in the medical field, that is now being used in a large number of disciplines to study a wide variety of materials and processes. In food science, MRI techniques allow the interior of foods to be imaged noninvasively and nondestructively. These images can then be quantified to yield information about several processes and material properties, such as mass and heat transfer, fat and ice crystallization, gelation, water mobidity, composition and volume changes, food stability and maturation, flow behavior, and temperature. This article introduces the fundamental principles of MRI, presents some of the recent advances in MRI technology, and reviews some of the current applications of MRI in food science research.

Food Analysis↗
PubMed1996

Does selective decontamination of the digestive tract reduce mortality for severely ill patients?

OBJECTIVE: To investigate the relationship between baseline risk of death and reduced mortality after selective decontamination of the digestive tract in intensive care unit patients. DESIGN: Analysis of data from a meta-analysis of 23 randomized, controlled trials. PATIENTS: A total of 4,142 adult intensive care unit patients from the 23 trials. MEASUREMENTS AND MAIN RESULTS: Mortality for patients receiving selective decontamination of the digestive tract treatment was analyzed as a function of baseline risk of death at study entry, using weighted least squares regression across all 23 trials. In testing whether the slope of the regression is different than 1.0, the observed t value is 3.32 (p < .004), suggesting that the efficacy of selective decontamination of the digestive tract in reducing mortality is significantly better in populations at high mortality risk at study entry. CONCLUSIONS: Mortality reduction from selective decontamination of the digestive tract appears related to the mortality risk of patients at the time of study entry. Future trials should consider using baseline risk assessment as part of trial design and outcome analysis.

Adult↗
PubMed1996

Planning patient services for intermediate care units: insights based on care for intensive care unit low-risk monitor admissions.

OBJECTIVE: To describe the technology and nursing services that would be required to care for intensive care unit (ICU) low-risk monitor admissions in an intermediate unit. DESIGN: Prospective, multicenter, inception cohort analysis. SETTING: Forty U.S. hospitals with > 200 beds, including 26 hospitals that were randomly selected and 14 that volunteered for the study. PATIENTS: A sample of 8,040 ICU patients admitted to the ICU for monitoring, who received no active life-support treatment on ICU day 1. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographic, physiologic, and treatment information were obtained during ICU days 1 to 7. A previously validated multivariate equation was used to identify 6,180 monitor admissions at low (< 10%) risk for receiving active treatment during their entire ICU stay. We used daily Therapeutic intervention Scoring System (TISS) data to identify the equipment, type and amount of nursing care, and the types of active treatment that would have been used had these ICU patients been admitted to an intermediate care unit. Mean day-1 ICU TISS scores were as follows: 16.4 for all patients; 18.3 for surgical patients; and 13.5 for medical admissions. Concentrated nursing care accounted for 89% and technologic monitoring for 11% of day-1 TISS points. Surgical admissions had a 2.8-day mean ICU length of stay and received an average of 16.5 TISS points per patient per day. Medical admissions had a 2.7-day mean ICU length of stay and received an average of 12.3 TISS points per patient per day. Subsequent active life-support therapy was received by 4.4% of these ICU low-risk monitor admissions. CONCLUSIONS: The services received by ICU low-risk monitor admissions provide insight regarding the equipment and nursing care that might be required, and the kinds of emergencies that might occur, if these patients were cared for in medical and surgical intermediate care units. Our data suggest that if ICU low-risk monitor patients were admitted to an intermediate care unit, they would mainly require concentrated nursing care (nurse/patient ratio of 1:3 to 1:4) and limited technologic monitoring.

APACHE↗
PubMed1996

A comparison of risks and outcomes for patients with organ system failure: 1982-1990.

OBJECTIVES: To compare the outcomes for patients with one or more organ system failures treated in 1988 to 1990 with those outcomes from 1979 to 1982; to document risk factors for developing organ system failure; and investigate the relationship of these factors to hospital survival. DESIGN: Prospective, multicenter, inception cohort analysis. SETTING: Sixty intensive care units (ICUs) at 53 U.S. hospitals. PATIENTS: A total of 17,440 ICU admissions treated in 1988 to 1990 and 5,677 ICU admissions treated in 1979 to 1982. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: At the time of organ system failure, patients were classified by demographic, physiologic, and diagnostic information. The type and number of organ system failures and physiologic responses were recorded for < or = 7 days of ICU treatment, and all patients were followed for status at hospital discharge. Hospital survival and the prognostic value of assessing the number of organ system failures were compared with risk assessment, based on use of a prognostic scoring system that estimated the patient's probability of hospital mortality. The incidence of organ system failure (48%) among patients treated in 1988 to 1990 was similar (44%) to the occurrence rate in patients in 1979 to 1982; and an identical proportion (14%) developed multiple organ system failure. There was a significant (p < .0003) improvement in hospital mortality for patients with three or more organ system failures on day 4 or later of organ system failure. However, overall hospital mortality rates from multiple organ system failure were not different over this 8-yr period. The most important predictor of hospital mortality was the severity of physiologic disturbance on the initial day of failure. Discrimination of patients by risk of hospital mortality was better using the prognostic scoring system on day 1 of organ system failure (receiver operating characteristic curve = 0.88) than using a model based on the number of organ system failures (receiver operating characteristic curve = 0.68). CONCLUSIONS: Organ system failure remains a major contributor to death in patients in ICUs. The incidence and overall outcome have not significantly changed over the past 8 yrs, but there has been significant improvement in survival for patients with persistent severe organ system failure. A continuous measure of individual patient severity of illness is a more sensitive and accurate method for describing patients and estimating outcome than counting the number of organ system failures.

APACHE↗
PubMed1996

Follow-up study on histogenesis of microcephaly associated with ectopic gray matter induced by prenatal gamma-irradiation in the mouse.

Brain malformation with ectopic gray matter was visualized with magnetic resonance imaging in small-sized heads of prenatally exposed atomic bomb survivors. The identical brain malformation was reproduced in mice and its histogenesis was studied in the present experiment. Pregnant mice were exposed to 60Co gamma-irradiation at a single dose of 1.5 Gy on embryonic day 13 (E13), and then injected intraperitoneally with 30 mg/kg BrdU on E15. The extensive dead cells appeared throughout the brain mantle at 6 hours (h) after exposure. On E16 cell aggregations formed rosettes. On E18 a high proportion of BrdU-labeled cells reached the superficial layers of the cortical plate with the remaining cells located in the ectopic neuronal masses. The quantitative study showed that labeled cells in layers II to III were fewer and those in layers IV to VI more numerous in the prenatally irradiated adult mice than in controls. The anti-GFAP immunostaining revealed that the glial fibers in the irradiated mice were preserved, but disorganized. These findings suggested that the majority of migrating neurons were able to arrive at their normal layers, but some neurons remained due to the interrupted migratory pathway and eventually formed ectopic neuronal masses beneath the subcortical white matter.

Age Factors↗
PubMed1996

Comparative cardiovascular effects of the angiotensin II type 1 receptor antagonists ZD 7155 and losartan in the rat.

Binding experiments show that ZD 7155 is a potent angiotensin II type 1 receptor antagonist. In this study this novel substance was studied in normotensive and hypertensive rats. The relative potency and duration of the antihypertensive effects of ZD 7155 were compared with those of the reference substance, losartan. The inhibitory effects of both compounds on angiotensin II-induced pressor actions were studied in the conscious normotensive Sprague-Dawley (SD) rat and in the conscious, spontaneously hypertensive rat (SHR). Arterial blood pressure and heart rate (HR) were obtained by direct intraarterial recording. Angiotensin II infusion was administered intravenously in the dose range 53.3 ng-12.8 micrograms kg-1 min-1 to the conscious rats. ZD 7155 was administered in a bolus dose of 1.082 mumol kg-1 (0.51 mg kg-1) and losartan in bolus doses of 2.165 and 6.495 mumol kg-1 (1.0 and 3.0 mg kg-1). In conscious SD rats, ZD 7155 and losartan behaved as competitive antagonists and the pressor response curve to angiotensin II was shifted to the right. Experiments in conscious SD rats also showed that ZD 7155 was approximately ten times as potent as losartan in suppressing the angiotensin II-induced pressor response (240 ng kg-1; 10 min infusion). In addition, experiments with conscious rats demonstrated that ZD 7155 could suppress the angiotensin II-induced pressor response for approximately 24 h when ZD 7155 was administered intravenously in a 1.082 mumol kg-1 bolus dose and angiotensin II was given at 240 ng kg-1 (in a 10-min infusion). Experiments in conscious SHRs using ZD 7155 (1.082 mumol kg-1) and losartan (6.495 mumol kg-1) as intravenous boluses indicated that both ZD 7155 and the reference compound losartan exhibited a significant antihypertensive effect. These results demonstrate that ZD 7155 is a potent angiotensin II-type 1 antagonist which is approximately ten times as potent as losartan in suppressing the angiotensin II-induced pressor response. Furthermore, ZD 7155 may suppress the angiotensin II-induced pressor response for 24 h and in the SHR ZD 7155 induces a pronounced and persistent antihypertensive effect.

Angiotensin Receptor Antagonists↗
PubMed1996

alpha-Trinositol: a functional (non-receptor) neuropeptide Y antagonist in vasculature.

Neuropeptide Y is a sympathetic co-neurotransmitter released with noradrenaline upon sympathetic nerve stimulation. This study describes the ability of a synthetic inositol phosphate, alpha-trinositol(D-myo-inositol 1,2,6-triphosphate; PP 56) to antagonize vasoconstrictor responses to neuropeptide Y in-vitro as well as in-vivo. In human and guinea-pig isolated arteries alpha-trinositol potently (10 nM to 1 microM extracellular concentration) suppressed the constriction evoked by neuropeptide Y alone, the potentiation by neuropeptide Y of noradrenaline-evoked constriction, and the neuropeptide Y-induced inhibition of relaxation. Moreover, in the pithed (areflexive) rat, a non-adrenergic portion of the pressor response to preganglionic sympathetic nerve stimulation was sensitive to alpha-trinositol. As studied in the recently cloned human (vascular-type) Y1 receptor, the action of alpha-trinositol does not occur through antagonism at the neuropeptide Y recognition site nor does it induce allosteric changes of this receptor. However, we found alpha-trinositol to inhibit the rise in intracellular Ca2+ as well as inositol triphosphate concentrations induced by neuropeptide Y. It is, therefore, proposed that alpha-trinositol represents a non-receptor, but yet selective antagonist of neuropeptide Y in vasculature, opening up the possibility to investigate involvement of neuropeptide Y in sympathetic blood pressure control and in cardiovascular disorders.

Adrenergic alpha-Antagonists↗
PubMed1996

The intracellular deletions of Delta and Serrate define dominant negative forms of the Drosophila Notch ligands.

We examined the function of the intracellular domains of the two known Drosophila Notch ligands, Delta and Serrate, by expressing wild-type and mutant forms in the developing Drosophila eye under the sevenless promoter. The expression of intracellularly truncated forms of either Delta (sev-DlTM) or Serrate (sev-SerTM) leads to extra photoreceptor phenotypes, similar to the eye phenotypes associated with loss-of-function mutations of either Notch or Delta. Consistent with the notion that the truncated ligands reduce. Notch signalling activity, the eye phenotypes of sev-DlTM and sev-SerTM are enhanced by loss-of-function mutations in the Notch pathway elements, Notch, Delta, mastermind, deltex and groucho, but are suppressed by a duplication of Delta or mutations in Hairless, a negative regulator of the pathway. These observations were extended to the molecular level by demonstrating that the expression of Enhancer of split m delta, a target of Notch signalling, is down-regulated by the truncated ligands highly expressed in neighbouring cells. We conclude that the truncated ligands act as antagonists of Notch signalling.

Amino Acid Sequence↗
PubMed1996

Distortion product otoacoustic emission test of sensorineural hearing loss: performance regarding sensitivity, specificity and receiver operating characteristics.

The performance of distortion product otoacoustic emissions (DPOEs) as a frequency-specific test of sensorineural hearing loss was evaluated in 142 ears of human adults with normal middle-ear function. The DPOE was measured with the stimulus levels of the two tones equal to 65 dB SPL (re 20 mu Pa) and the ratio between the two frequencies 1.2. In the DPOE test, the cochlear function of an ear at a test frequency was predicted to be normal or abnormal depending upon whether the DPOE level with the geometric mean of the two stimulus frequencies at the test frequency was greater or less than a criterion. The DPOE test outcomes were evaluated against the pure-tone hearing threshold as the standard. We found the sensitivity, specificity and predictive efficiency of the test to be 85-89% at 6000 and 4000 Hz, 82-83% at 2000 Hz and 78-79% at 1000 Hz, respectively. The performance was also evaluated using decision theory in terms of the area under the receiver operating characteristics. The latter was found to range from 0.90 (for 1000 Hz) to 0.94 (for 6000 Hz). These findings support the conclusion that the DPOEs can form a useful frequency-specific objective test of cochlear function.

Acoustic Impedance Tests↗
PubMed1996

Characterization of neuropeptide Y receptors mediating contraction, potentiation and inhibition of relaxation.

In addition to its direct vasoconstrictive effect, neuropeptide Y (NPY) potentiates noradrenaline-(NA) induced contraction and inhibits acetylcholine-(ACh) induced relaxation: The aim of the present study was to elucidate the NPY receptor subtypes responsible for mediating these three responses. NPY, peptide YY (PYY) and pro34NPY (a NPY Y1 receptor agonist) induced equipotent and equally strong concentration-dependent contractions of guinea pig basilar arteries. NPY13-36 (a NPY Y2 receptor agonist), however, caused only weak contraction with significantly lower potency. The NPY-induced contraction was significantly inhibited by the selective NPY Y1 receptor antagonist BIBP3226 (1 microM). NPY, PYY and pro34NPY but not NPY13-36 significantly potentiated the NA-induced contraction in guinea pig mesenteric arteries. The potentiation was significantly inhibited by BIBP3226 (1 microM). In precontracted guinea pig basilar arteries, ACh induced a concentration-dependent relaxation which was significantly inhibited by NPY, PYY and NPY13-36 but not by pro34NPY. BIBP3226 had no significant effect on the NPY-induced inhibition of the relaxation. These results suggests that the NPY Y1 receptors mediate the direct contraction and the potentiation of the NA-induced contraction but not the inhibition of the ACh-induced relaxation. This effect seems to be mediated by another NPY receptor subtype, presumably by the Y2 receptor, as judged from the agonist potency order.

Acetylcholine↗
PubMed1996

[The purification and analysis of S-antigen in rabbit retina].

OBJECTIVE: S-antigen from rabbit retina was isolated and purified to investigate the immune mechanisms of experimental autoimmune uveoretinitis (EAU) and lay a foundation for its experimental treatment. METHOD: Two-step ion exchange chromatography was used for the purification of S-antigen and it was analyzed. RESULT: The analytical studies show that the molecular weight of the purified S-antigen is 55,000, its isoelectric point is 6.40, and non-polar amino acid constitutes a relatively large proportion in its amino acids. Scanning tunnel electron microscope was used to investigate the configuration of S-antigen. It is elliptic globe-like. The purified S-antigen successfully induced the model of EAU. CONCLUSION: S-antigen purified by two-step ion exchange chromatography can be used for its own analytical studies and induction of EAU model.

Amino Acids↗
PubMed1996

[Uterine papillary serous carcinoma and papillary endometrial carcinoma: analysis of clinical biological behaviors of 56 cases].

OBJECTIVE: To characterize the clinical biological behavior and the pathological morphology of uterine papillary serous carcinoma and papillary endometrial carcinoma. METHODS: This is a retrospective analysis of 56 patients with papillary endometrial cancer treated at Cancer Hospital. Chinese Academy of Medical Sciences from January, 1981 to December, 1993. Of the 56 cases, 15 were uterine papillary serous carcinomas (UPSC), 41 papillary endometrial carcinomas (PEC). One hundred and sixty patients with endometrial adenocarcinoma (AC) were submitted as control group. RESULTS: 26.7% of UPSC, 14.6% of PEC and 5.6% of AC patients had stage III or IV by clinical examination (P < 0.05), whereas 53.3% of UPSC, 20.8% of PEC and 12.1% of AC patients has extrauterine disease at surgery (P < 0.01). Deep myometrial invasion occurred in 75.0% of UPSC, 41.7% of PEC, and 32.3% of AC patients (P < 0.01). An increasing gradient of 5 year survival rate (life table method) was observed from UPSC (45.7%) to PEC (61.9%) to AC (90.3%) in their early stage (stage I-II) (P < 0.01). Upper abdominal spread was a common finding in UPSC which had a high rate of persistent disease (46.2%). The pelvis was the predominant involving site in PEC with a high frequency of recurrence and metastasis (31.0%). CONCLUSIONS: The presence of papillary features in endometrial carcinoma is an important prognostic indicator. The prognosis of PEC is better than UPSC, but worse than AC.

Adult↗
PubMed1996

[A study on changes of levels of products of lipid peroxidation in retina of rat with experimental autoimmune uveoretinitis].

OBJECTIVE: To understand the mechanisms of the retinal tissue destruction of rat with experimental autommune uveoretinitis (EAU) induced by rabbit retinal soluble antigen. METHOD: The levels of the following products of lipid peroxidation were determined at different times, conjugated dienes, malondialdehyde, fluorochrome lipid and lipid hydrogen peroxide. RESULTS: In the process of EAU, the levels of products of lipid peroxidation in the retina were increased gradually in various degrees. CONCLUSION: It is suggested that the damage from lipid peroxidation mediated by free radicals of the retina be one of the factors which induces the retinal destruction in EAU.

Animals↗
PubMed1996

[An experimental study on corneal collagen shield vehicle for delivery of pilocarpine].

OBJECTIVE: The study was designed to clarify the role of corneal collagen shield made in China as a drug vehicle for the delivery of pilocarpine in different ways. METHODS: 80 eyes of New Zealand white rabbits were randomly divided into three groups, corneal collagen shield immersed with pilocarpine, corneal collagen shield with topical application of pilocarpine and synthetic collagen pilocarpine shield. At 0.5, 1, 3 and 6 hours after the delivery, the aqueous concentrations of pilocarpine and the pupillary sizes of all the eyes were measured. RESULTS: This study showed that shortly after the delivery of pilocarpine in the 3 groups, in spite of difference in ways of its delivery, its aqueous concentrations reached a relatively high level and maintained for more than six hours, the shield acting as a temporary "drug source". The aqueous pharmacokinetics of corneal collagen shield for pilocarpine delivery was consistent with the first-order kinetics and it was confirmed by the observations of miotic response. CONCLUSIONS: The corneal collagen shield made in China is a fine vehicle for drug delivery.

Animals↗
PubMed1996

[Extraction technology of effervescent granules for arresting cold pain optimized by orthogonal tests].

In the extraction technology of Effervescent Granules for Arresting Cold Pain (Hantongding Paoteng Chongji), the drug combinative modes, solvent pH and drug granularity were optimized by orthogonal tests, with the total alkaloid, paeoniflorin and glycyrrhetinic acid as indexes. The experimental results show that it is better to decoct together all the recipe ingredients, with water of pH2 for the first decoction, then water of pH8 for the second decoction, and to make its granularities ranging from the original herbal pieces to particles which can pass through a No. 2 sieve.

Alkaloids↗
PubMed1996

[Changes in calcium uptake and Ca(2+)-ATPase activity of cardiac sarcoplasmic reticulum in rat associated with hypoxia of various degrees].

Two groups of Wistar rats were exposed to hypoxia at 5000 to 8000 m high above the sea level in a hypobaric chamber for 7 days. The effects of hypoxia on left cardiac function, sarcoplasmic reticulum (SR) Ca2+ ATPase activity and SR calcium uptake were observed. The results indicated that the left ventricular function exposed to hypoxia at 5000 m was much higher than that at 8000 m. Calcium uptake and Ca2+ ATPase activity of the exposed groups decreased significantly compared with those of the control group, but they were much higher in the exposed group at 5000 m than at 8000 m. These results suggest that the changes in calcium uptake and Ca2+ ATPase activity of SR may be one of the important biochemical indicators for cardiac function alterations associated with hypoxia.

Animals↗