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T Yu

Publications and source records attributed to T Yu.

70 records · Page 4Linked to original sources
PubMed1980

Potential organ- or tumor-imaging agents XIX: radioiodinated antiarrhythmic drugs as potential myocardial imaging agents.

Iodinated and radioiodinated analogs of propranolol and N,N-dimethylpropranolol were synthesized wherein an iodophenyl moiety replaced the naphthalene ring of the parent drug. These new compounds were evaluated not only for their beta-adrenergic blocking and antiarrhythmic activities but also for their ability to accumulate selectively in myocardial tissue. Like propranol, the iodinated analogs displayed comparable beta-blocking and antiarrhythmic activity, and the order of potency was ortho- > meta- > para-iodophenyl. Quaternization of propranolol and the iodinated analogs eliminated the beta-adrenergic blocking activity but retained the antiarrhythmic property of the secondary amine precursors. Among the quaternary salts, the antiarrhythmic potency was meta- > ortho- > para-iodophenyl. Tissue distribution of the radioiodinated derivatives revealed that only the quaternary derivatives were selectively accumulated in myocardial tissue. These results demonstrate that an iodophenyl ring can substitute for th naphthalene ring in propranolol and its quaternary salt without significant alteration of pharmacological properties. The radioiodinated quaternary derivatives may be useful pharmacological tools in experiments aimed at relating antiarrhythmic activity to myocardial uptake.

Adrenergic beta-Antagonists↗
PubMed1978

Adrenal imaging agents: rationale, synthesis, formulation and, metabolism.

In this introductory paper on radionuclide adrenal imaging, the rationale, synthesis, formulation, and metabolism of two clinically well-established and one promisinmg adrenocortical imaging agents are reviewed. Their present clinical utility is reviewed in a separate presentation in this issue. Progress to date in developing a positive imaging agent of the adrenal medulla and tumors of chromaffin tissue will be given brief consideration because there is, as yet, no clinically successful radiolabeled adrenal medulla imaging agent.

Adrenal Glands↗
PubMed1977

A radioiodinated bretylium analog as a potential agent for scanning the adrenal medulla.

Studies with radioiodinated bretylium analogs (RIBA) suggested that the p-isomer was capable of concentrating in adrenal medulla. The present studies with 125I-p-RIBA in rats and dogs confirm this property and show its marked and persistent affinity for the adrenal medulla. Analogous studies with 14C-p-IBA indicate that it is the quaternary form of the drug that is retained by the adrenal and that high thyroidal radioactivity following 125I-p-RIBA administration is due to in vivo deiodination of the drug.

Adrenal Gland Diseases↗
PubMedDate not supplied

Immobilization of glucose oxidase with the blend of regenerated silk fibroin and poly(vinyl alcohol) and its application to a 1,1'-dimethylferrocene-mediating glucose sensor.

The structure and properties of the blend of regenerated silk fibroin (RSF) and poly(vinyl alcohol) (PVA) were investigated. The two polymers in the blend are in the state of phase segregation. Infrared (IR) spectra indicate that the RSF in the blend maintains its intrinsic properties, thus, ethanol treatment can transfer silk I structure of RSF to silk II structure. The water absorption property and mechanical property of the blend are improved in comparison with those of RSF. The blend maintains the major merit of RSF, that is, it can immobilize glucose oxidase on the basis of the conformational transition from silk I structure to silk II structure. The properties of the immobilized enzyme are examined. Moreover, the second generation of glucose sensor based on the immobilized enzyme is fabricated and it has a variety of advantages including easy maintenance of enzyme, simplicity of construction, fast response time and high stability.

Biosensing Techniques↗
PubMedDate not supplied

Angiogenesis inhibitor TNP-470 reduces human pancreatic cancer growth.

In this study we investigated the effects of the angiogenesis inhibitor TNP-470 on human pancreatic cancer cells in vitro and in vivo. The action of TNP-470 on vascular endothelial growth factor (VEGF) was also assessed. In vitro human pancreatic cancer cells (MIAPaCa-2, AsPC-1, and Capan-1), and human umbilical vein endothelial cells (HUVEC) were exposed to increasing concentrations (1 pg/ml to 100 microg/ml) of TNP-470. Cell proliferation was assessed after 3 days by cell count and MTT assay. In vivo, 5 x 10(6) pancreatic cancer cells were injected subcutaneously into nude mice. Four weeks later, 1 mm3 fragments of the resulting tumors were implanted into the pancreas of other mice. Animals received either TNP-470 (30 mg/kg every other day) or vehicle subcutaneously for 14 weeks. The volume of the primary tumor and metastatic spread were determined at autopsy. Concentrations of VEGF were determined in serum (VEGF(S)) and ascites (VEGF(A)) by enzyme-linked immunosorbent assay. Microvessel density was analyzed by immunohistochemistry in CD31-stained tumor sections. In vitro, proliferation and viability of the human pancreatic cancer cell lines were significantly inhibited at high concentrations of TNP-470 (> 1 microg/ml). In contrast, TNP-470 effectively decreased the growth of HUVEC at 100 pg/ml. In vivo, tumor volume and dissemination scores were significantly lower in all three pancreatic cancer cell lines. VEGF(S) and VEGF(A) were not different between treated groups. Treatment with TNP-470 significantly reduced neoangiogenesis in tumors of all three human pancreatic cancer cell lines: MIAPaCa-2 = 74.8 +/- 7.8/0.74 mm2 vs. 24.8 +/- 3.7/0.74 mm2; AsPC-1 = 65.3 +/- 5.0/0.74 mm2 vs. 26.0 +/- 3.4/0.74 mm2; and Capan-1 = 82.2 +/- 5.8/0.74 mm2 vs. 26.9 +/- 2.5/0.74 mm2 (P < 0.001). However, survival was not statistically different between groups. TNP-470 reduced tumor growth and metastatic spread of pancreatic cancer in vivo. This was probably due to the antiproliferative effect of the agent on endothelial cells rather than to the direct inhibition of pancreatic cancer cell growth. TNP-470 activity was not associated with alteration of VEGF secretion.

Adenocarcinoma↗
PubMedDate not supplied

Changes at a human immunodeficiency virus testing clinic in the prevalence of unsafe sexual behavior among men who have sex with men.

GOAL: Given reductions in risky sexual behavior reportedly occurring during the 1980s among men who have sex with men, the authors sought to assess if such trends are continuing. STUDY DESIGN: The authors analyzed initial visit data for 4,880 men who presented at a human immunodeficiency virus testing clinic from 1988 through 1993 and who reported any male partners during the preceding 12 months. RESULTS: From 1988 to 1993, the percent of men who have sex with men reporting any oral sex (virtually all of which was unprotected) or any anal sex (more than two-thirds of which was unprotected) during the previous 6 months increased from 78% to 90% (P < 0.001) and from 47% to 55% (P = 0.6), respectively. Adjusting for demographics and numbers of partners did not change results. CONCLUSIONS: Unprotected anal sex persists, whereas unprotected oral sex is increasing among men who have sex with men and who present for human immunodeficiency virus testing. New strategies are needed to reduce human immunodeficiency virus risk among men who have sex with men.

Adult↗
PubMedDate not supplied

Using computerized data to identify adverse drug events in outpatients.

OBJECTIVE: To evaluate the use of a computer program to identify adverse drug events (ADEs) in the ambulatory setting and to evaluate the relative contribution of four computer search methods for identifying ADEs, including diagnosis codes, allergy rules, computer event monitoring rules, and text searching. DESIGN: Retrospective analysis of one year of data from an electronic medical record, including records for 23,064 patients with a primary care physician, of whom 15,665 actually came for care. MEASUREMENT: Presence of an ADE; sensitivity and specificity of computer searches for ADE. RESULTS: The computer program identified 25,056 incidents, which were associated with an estimated 864 (95 percent confidence interval [CI], 750-978) ADES. Thus, the ADE rate was 5.5 (CI, 5.2-5.9) per 100 patients coming for care. Furthermore, in 79 (CI, 68-89) ADEs, the patient required hospitalization, resulting in an estimated rate of 3.4 (CI, 2.7-4.3) admissions per 1,000 patients. The sensitivity of the search methods for identifying ADEs was estimated to be 58 (CI, 18-98) percent, and the estimated specificity was 88 (CI, 87-88) percent. The positive predictive value was 7.5 (CI, 6.5-8.5) percent, and the negative predictive value was 99.2 (CI, 95.5-99.98) percent. Compared with age and gender-matched controls with no positive screen, patients with ADEs had twice as many outpatient visits and were taking nearly three times as many drugs. Antihypertensives, ACE-inhibitors, antibiotics, and diuretics were associated with 56 (CI, 47-65) percent of ADES. Among ADEs, 23 (CI, 16-32) percent were life-threatening or serious, and 38 (CI, 29-47) percent were judged preventable. CONCLUSION: Computerized search programs can detect ADEs, and free-text searches were especially useful. Adverse drug events were frequent, and admissions were not rare, although most hospitals today do not identify them. Thus, such detection programs demonstrate "value-added" for the electronic record and may be useful for directing and assessing the impact of quality improvement efforts.

Adverse Drug Reaction Reporting Systems↗
PubMedDate not supplied

Antitumor and antitumor-promoting actions of macrophages and their relationship with estrogen.

Silica provides, in fact, a remarkable example of selective toxicity for macrophage by a substance of simple chemical composition and low chemical reactivity. Intraperitoneal injection of silica resulted in an increase of growth rate of subcutaneously implanted mouse sarcoma 180 (S180) in female BALB/c mice and of tumor incidence of two-stage mouse skin carcinogenesis in female ICR mice, but did not show any significant effects on tumor growth and carcinogenesis in male mice. In contrast, local administration of homologous macrophages led to the decrease of growth rate of subcutaneously implanted mouse S180 in female BALB/c mice and of tumor incidence of two-stage mouse skin carcinogenesis in female ICR mice. On the other hand, estradiol, estradiol plus macrophages or a large number of macrophages alone inhibited the tumor growth in male mice. It should be noted that estradiol plus macrophages had the most potent antitumor action among them. These results suggest that macrophages, especially estrogen-activated macrophages, may play an important role in antitumor and antitumor-promoting actions of organisms.

Animals↗
PubMedDate not supplied

Carcinomatous encephalitis (miliary metastases): lack of contrast enhancement.

Carcinomatous encephalitis is a rare form of brain metastasis in which there is diffuse miliary spread of punctate tumor nodules in a perivascular distribution. In this case, these tiny tumor nodules were seen throughout the cortical and basal gangliar gray matter only on T2-weighted images. Contrast-enhanced CT and T1-weighted MR images did not demonstrate these tumor nodules.

Brain↗