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Biomedical subjects

Y Yu

Publications and source records attributed to Y Yu.

At least 577 records · Page 32Linked to original sources
PubMed1991

The demography of disability.

"This article examines selected demographic characteristics of disabled persons. It analyses the general levels of disablement in various countries and compares their age and sex compositions. Since variations in methods of data collection and classification among countries have contributed greatly to the differences in the measurement of levels of disablement, this paper discusses the need for common approaches to collection, classification, tabulation and analysis so as to improve understanding of the issues of disability."

Age Factors↗
PubMed1991

Functional analysis of the CPS I upstream sequences with a cat assay.

Expression plasmids (pKCPS-CAT) containing carbamyl phosphate synthetase (CPS I) upstream sequences of different lengths were constructed, and the function and characteristics of the sequences were studied with the CAT assay. Results showed that the CPS I upstream sequences exerted highly tissue-specific control on CPS I gene expression, and the -113 approximately -38 bp region relative to the cap site was found to be indispensable for CPS I gene transcription. The -1700 approximately -161 bp region contains sequences which confer an enhancing effect on CPS I gene transcription. Dexamethasone and thioproline (a differentiation inducer) showed enhancing effects on CPS I gene transcription in hepatoma cells. These results would have significance in studies on the gene regulation of CPS I associated with the mechanism of hepatocyte differentiation and carcinogenesis.

Antineoplastic Agents↗
PubMed1991

Studies on antipeptic ulcer agents: the quantitative structure-activity relationship analysis of heterocyclic aldehyde N4-substituted phenyl (thio) semicarbazones.

Forty-five condensation products of furan-, pyrrole- and N-methyl pyrrole-alpha-carboaldehyde with N4-3- or N4-4-substituted phenyl semicarbazones and thiosemicarbazones were designed to optimize the antiulcer activity of a previously derived lead structure, formula II. Quantitative structure-activity relationships revealed that among the series of semicarbazones, increasing hydrophobicity and the introduction of electron-donating groups into the phenyl ring raise the antiulcer activity. Generally, semicarbazones are more active than the corresponding thiosemicarbazones. The wide gulf between the activity and toxicity of two derivatives (Compounds III and IV) necessitates further investigation of their pharmacological effects.

Anti-Ulcer Agents↗
PubMed1991

Induction of cytochrome P450 isozymes in human amnion FL cells and its application to the biological detection of mutagens.

Using AHH, EROD, ECOD and APND as marker enzymes and 3-MC, beta-NF, NE and PB as inducers, inducible cytP450 IA and IIB gene expression was demonstrated in the human amnion FL cell line; these cells possess a broad spectrum of drug-metabolizing enzymes. Maximum induction was observed following co-treatment with 3-MC and NE. Both constitutive and induced AHH were proved to have the characteristics of cytP448-dependent mixed-function oxygenases. Induced cytP450 isozyme activity remained at a high level for 24-36 h after removal of the inducer. The induced FL cells were demonstrated to activate common promutagens/procarcinogens in UDS and ADPRT-mediated decrease of NAD content assay systems. This new design can be used as a simplified mutagen screening system: no supplemental liver microsomal activation system is needed.

Amnion↗
PubMed1991

[Ultrastructural study of adenolymphoma].

Ultrastructure of 10 adenolymphomas of parotid gland were studied. The neoplastic epithelium consists of "oncocytes" which are arranged in pseudostratified pattern. Their cytoplasm is almost totally packed with a large numbers of hypertrophic mitochondria showing a variety of peculiar forms. The amount and alteration of the mitochondria gradually increase in the order of pyramidal cell, common columnar cell and degenerated columnar cell. This might be a process of transposition representing degeneration due to metabolic disorder in the tumor. The obvious alterations of mitochondria are found in the cases with not only "hot" nodule but also "cold" nodule shown in the studies of 99mTc scintigraphy. There seems no relationship between "hot" nodule and alteration of mitochondria.

Adenolymphoma↗
PubMed1991

[C fiber is not necessary in electroacupuncture analgesia, but necessary in diffuse noxious inhibitory controls (DNIC)].

Experiments were carried on rats. We applied capsaicin topically on sciatic nerve and used the techniques of extracellular recording and nerve trunk recording, Our results showed that the size of C compound action potentials in nerve trunk and C fiber response of spinal cord WDR neurons were decreased by at least 70% (mean) after topical application of capsaicin (250 micrograms) on the nerve, but A compound action potentials and A fiber response did not change significantly. It indicated that capsaicin blocked C fiber conduction selectively. Electroacupuncture (EA: 100 Hz, 0.1 ms, 3V) applied on left Zusanli (S36) and Sanyinjiao (Sp6) points inhibited C fiber response of spinal WDR neurons in the right side. The effect was similar to animal behavior analgesia elicited by EA. After applying capsaicin (250 micrograms) topically on left sciatic nerve, the inhibitory effect of EA on WDR neurons remained essentially intact (from 61.3 +/- 12.0% to 59.0 +/- 11.6%, n = 6, P greater than 0.05). It indicated that C fiber was not important in EA analgesia. Noxious heat (NH) applied on left hind paw by immersing the hind paw into 52 degrees C water inhibited C fiber response of spinal WDR neurons in the right side. It was called diffuse noxious inhibitory controls (DNIC). After applying capsaicin (250 micrograms) topically on left sciatic nerve, the inhibitory effect of NH on WDR neurons was dramatically decreased (from 77.7 +/- 8.5% to 8.1 +/- 8.9%, n = 6, P less than 0.001). It indicated that C fiber was important in DNIC. Both inhibitory effects of NH and EA were not changed by vehicle treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗
PubMed1991

[Histopathology of experimental hepatic amebiasis].

The method of intrahepatic inoculation was successfully used to establish an experimental model of hepatic amebiasis in golden hamsters for studying its pathological morphology. Three types of macroscopic liver lesions, i.e., isolated abscess, multinodular abscess and ruptured lesion were described. On light microscopy the alteration and the proliferation type lesions were found as distinct pathological characteristics of the early and advanced hepatic amebiasis respectively. The development pattern of hepatic amebiasis and the pathogenicity of Entamoeba histolytica were discussed.

Animals↗
PubMed1990

Structural requirements of iron-responsive elements for binding of the protein involved in both transferrin receptor and ferritin mRNA post-transcriptional regulation.

The synthesis of both transferrin receptor (TfR) and ferritin is regulated post-transcriptionally by iron. This is mediated by iron responsive elements (IREs) in the 5'- and 3'-untranslated regions, respectively, of TfR and ferritin mRNAs. Although these IREs have different sequences, they both form a characteristic stem-loop. We used competition assays and partial peptide mapping of UV-crosslinked ferritin and TfR IRE-protein complexes to show that the cytosolic protein binding to the ferritin 5'-IRE, the iron-responsive element binding protein (IRE-BP), also binds to TfR 3'-IREs. To identify the structural requirements necessary for RNA-protein binding, ferritin IRE RNAs were synthesized which contained altered secondary structures and base substitutions. Affinities of these RNAs for IRE-BP were assayed in RNA-protein binding gels. Substitutions disrupting base-pairing of the stem prevented IRE-BP binding. Substitutions which restored base-pairing also restored IRE-BP binding. We conclude that the IRE-BP binds to both ferritin and TfR IREs and recognizes a particular IRE conformation.

Animals↗
PubMed1990

Brain structures important for solving a sawdust-digging problem in the rat.

Young rats subjected to bilateral lesions to one of 37 different brain sites were initially trained to traverse a narrow runway to reach a goal box containing water. The test involved blocking a portion of the runway with sawdust and determining whether the animals would burrow through the sawdust to gain access to the goal box. Lesions to 30 brain sites produced deficient performance on the sawdust-digging problem. This study, combined with earlier investigation of 11 additional brain sites, shows that 41 of 48 total brain sites are involved in this task. These findings suggest that underlying brain mechanisms include a nonspecific mechanism and several specific mechanisms, such as visuospatial-attentional, visual discrimination, vestibular-proprioceptive-kinesthetic discrimination, response flexibility, but much less place learning mechanisms.

Animals↗
PubMed1990

Heparinless extracorporeal bypass for treatment of hypothermia.

In an attempt to assess the changes occurring to the coagulation profile during internal active core rewarming with partial cardiopulmonary bypass (CPB) without heparin anticoagulation, five pigs were anesthetized, and a model for severe to moderate hypothermia was created. Femoral-femoral bypass with Bio-Pump, heat exchanger, and a membrane oxygenator were used during the rewarming for 64.8 +/- 8.5 minutes. There were no statistically significant changes in platelet count, platelet index, activated clotting time (ACT), partial thromboplastin time (PTT), prothrombin time (PT), fibrinogen, fibrinogen index and fibrin split products (p greater than 0.05). There were no thromboembolic sequelae seen at autopsy. The components of the CPB circuit showed no signs of formation of aggregates or thrombi. The results of this study are attributed to the nonthrombogenic, atraumatic design of the Bio-Pump and the enhanced physiological fibrinolysis seen in the first hour of CPB. We concluded that heparinless CPB may serve as a safe alternative for active core rewarming for severe to moderate hypothermia.

Animals↗
PubMed1990

Studies on antipeptic ulcer agents: a structure-activity relationship analysis of aldehyde semicarbazones and aryl hydrazones.

Twenty-eight condensation products of heterocyclic-a-carboaldehydes with N-aminooxazolidones, semicarbazides, thiosemicarbazides and benzoxycarbonyl hydrazide were synthesized so as to deduce the antiulcer pharmacophore or fragment of furazolidone (I), a prototype which has shown therapeutic efficacy in patients with gastric and duodenal ulcers. SAR analysis of the compounds indicated that the substitution of furan, thiophene, pyrrole or N-methyl pyrrole rings for 5-nitrofuran and the cleavage of the oxazolidone ring did not fully destroy the activity. The electron density of the carbonyl group was found to be of importance. A lead structure, therefore, was derived for further optimization.

Animals↗
PubMed1990

ADPRT-mediated decrease of cellular NAD content and the detection of chemically induced DNA damage--development of a new short-term screening test for mutagens.

It was found that the DNA-damaging agents N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), methyl-methanesulphonate (MMS) and 4-nitroquinoline-N-oxide (4NQO) could stimulate ADP-ribosyl transferase (ADPRT) activity and reduce the cellular NAD content in a dose-dependent way. The reduction of NAD after DNA damage could be partially or completely prevented by ADPRT inhibitors, 3-aminobenzamide or nicotinamide, which showed no influence on reduction of NAD induced by metabolic blocking agents. Therefore, a simple and specific method to detect DNA-damaging mutagens by measuring ADPRT-mediated decrease of cellular NAD content was explored. Using beta-naphthoflavone, a mixed function oxygenase inducer, together with induced or uninduced human amnion FL cells, it was found that aflatoxin B1, benzo(a)pyrene, 2-acetylaminofluorene, 9,10-dimethylanthracene and ethylcarbamate could induce the ADPRT-mediated decrease of cellular NAD content, while 4-acetylaminofluorene, anthracene, isopropyl-N-(3-chlorophenyl)-carbamate, beta-propiolactone, gamma-butyrolactone, cyclophosphamide and safrol could not. The results indicate that this is a cheap and specific method to detect DNA damage caused by chemical carcinogens/mutagens with a specificity approaching that of the unscheduled DNA synthesis assay.

Amnion↗
PubMed1990

Silk-induced asthma in children: a report of 64 cases.

A total of 64 children less than 15 years of age with asthma caused by silk were studied. The diagnosis was based on a history of wheezing, positive skin tests to silk, positive conjunctival or nasal provocation tests, or serum IgE-Sw (silk waste). The average age of onset was 4 years 2 months. Sex ratio (M:F) was 3.6:1. A positive skin test is essential for the diagnosis. Conjunctival provocation tests were performed in 80% of cases because of reliability, safety, and convenience. The first symptom appeared an average of 10 months after initial exposure to silk. In 61% of patients, asthma was accompanied by allergic rhinitis but in only 14% of cases by conjunctivitis. In most cases, asthma occurred in winter, due to seasonal use of bed quilts or clothes filled with silk. Silk is a highly potent allergen. The average mean wheal diameter elicited by silk in prick testing was larger than two histamine equivalent prick tests. A cross reactivity exists among mulberry silk, and silkworm cocoons, batryticated silkworms, and silkworm chrysalis.

Adolescent↗
PubMed1990

Immunopotentiating effect of traditional Chinese drugs--ginsenoside and glycyrrhiza polysaccharide.

The immunopotentiating effects of the traditional Chinese drugs Ginsenoside (GS) and Glycyrrhiza polysaccharide (GPS) are reported. It was demonstrated that GS promotes the phagocytic activity of plaque-forming cells (PFC) and enhances the mitogenesis of T and B lymphocytes primed by mitogens. The mechanism of these effects is related to the ratio of cGMP to cAMP. GS also plays a role in the NKC-IFN-IL-2 regulatory system, inhibits the growth of tumor cells, and antagonizes the suppression of ADCC and NK cytotoxicities in mice with surgical stress. GS exhibits bidirectional effects on immunological functions. GPS increases the phagocytosis of macrophages, induces macrophages to secret IL-1, enhances both NK and ADCC activities, behaves as a mitogen of B lymphocytes, inhibits the multiplication of several viruses, and induces the release of IFN from spleen cells.

Adjuvants, Immunologic↗
PubMed1990

Preventive effect of Fluosol-DA for paraplegia encountered after surgical treatment of the thoracic aorta. Preliminary results in a dog model.

The effectiveness of Fluosol-DA (Green Cross Corporation, Osaka, Japan) on circulatory dynamics and neurologic outcome in dogs with ischemic spinal cord injury produced by aortic crossclamping was tested. The control group (receiving saline solution) had an elevated mean aortic proximal pressure (112.9 +/- 30.2 mm Hg versus 175.3 +/- 20.5 mm Hg, p greater than 0.05) and a drastic drop in mean distal aortic pressure (112.9 +/- 30.2 mm Hg versus 29.8 +/- 11.2 mm Hg, p less than 0.05). Although the same trend occurred in dogs treated prophylactically with Fluosol-DA, these changes were not statistically significant. However, there was a significant difference in mean distal aortic pressure during the ischemic phase between the two groups (58.9 +/- 16.0 mm Hg versus 29.8 +/- 11.2 mm Hg, p less than 0.05). Postoperatively all animals had mean arterial pressures within the normal range. All dogs in the control group were paraplegic (partial or complete); the treatment group had one dog with partial paraplegia. The difference between the mean neurologic scores of the two groups was of high statistical significance (3.7 +/- 0.5 versus 1.6 +/- 1.0, p less than 0.05). Our preliminary results show that prophylactic use of Fluosol-DA has favorable effects on hemodynamics and neurologic outcome in dogs with spinal cord ischemia produced by aortic crossclamping. The high propensity of the drug to carry oxygen and carbon dioxide and to provide nutritional support to the ischemic area with resultant improvement in local microcirculation and blood rheology are some speculative mechanisms advocated for these changes.

Animals↗