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Biomedical subjects

T Yu

Publications and source records attributed to T Yu.

106 records · Page 6Linked to original sources
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

Mechanisms of reversal of adriamycin resistance in human ovarian carcinoma cell line by ultrasound.

The aim of this study was to investigate the reversal of adriamycin resistance in human ovarian cancer cells by ultrasound exposure from perspectives of apoptosis and mdr1 gene. Apoptosis was determined by flow cytometry and mdr1 level by reverse transcription-polymerase chain reaction (RT-PCR). Apoptosis indexes were improved in groups in which ultrasound exposures were applied. RT-PCR did not support that insonation-decreased mdr1 level. These findings suggested that the ultrasound-enhanced therapeutic efficacy was not mediated via modulating gene expression, and ultrasound maybe lowered thresholds for apoptosis and oncosis in chemoresistant ovarian cancer cells.

Antineoplastic Agents↗
PubMedDate not supplied

Ultrastructure alterations in adriamycin-resistant and cisplatin-resistant human ovarian cancer cell lines exposed to nonlethal ultrasound.

Human ovarian cancer cell lines, SKOV3 and its adriamycin-resistant substrain SKOV3/ADR and COC1 and its cisplatin-resistant substrain COC1/DDP, were exposed to nonlethal ultrasound. Ultrastructures in sham-insonated and insonated cells were inspected by transmission electron microscopy, and cytochrome C in cytosol was determined by enzyme-linked immunosorbent assay. Ultrasound exposure led to no significant changes in SKOV3/ADR cells, but tumid mitochondria occurred in SKOV3 cells. Mitochondria changes were also detected in some exposed COC1 and COC1/DDP cells. Apoptotic bodies could be detected in either control or insonated COC1/DDP cells. A few exposed COC1/DDP cells became reticular. Cytochrome C in cytosol in exposed SKOV3/ADR cells was increased but that in exposed COC1/DDP cells was decreased. These findings revealed that the bioeffect of ultrasound on chemosensitive cells was not identical to that of chemoresistant ones, and ultrasound was a potential approach for treatment of drug-resistant ovarian cancers.

Antibiotics, Antineoplastic↗
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

Stratification and oxidation-reduction potential change in an aerobic and sulfate-reducing biofilm studied using microelectrodes.

Recent studies in aerobic-nitrifying biofilms demonstrated the heterogeneity of biofilms used in wastewater treatment and led to modifications of the homogeneous assumptions in the conventional biofilm kinetic models. However, the stratification in aerobic-anaerobic biofilms has not been well investigated because of a lack of effective experimental tools. In this study a suite of microelectrodes, recently developed in the authors' laboratory, was used to examine the stratification of microbial processes and the change of oxidation-reduction potential (ORP) within an aerobic, sulfate-reducing biofilm. The microelectrodes have tip diameters of 3 to 20 microm and a high spatial resolution. They were used to measure the profiles of oxygen, total dissolved sulfide, ORP, and pH as a function of depth in the biofilm. The biofilm reactor was used to treat an azo-dye-containing wastewater with a chemical oxygen demand of 160 mg/L. The reactor bulk-phase dissolved oxygen concentration of the biofilm was 1.7 mg/L. The experimental results demonstrated that the microbial processes in the biofilm were stratified. In this biofilm, aerobic oxidation took place only in a shallow layer of 0.55 mm near the surface and sulfate reduction occurred in the deeper anoxic zone. The ORP changed with the shift of primary microbial process. The ORP was +362 mV at the biofilm surface and -166 mV near the substratum. Near the interface between the aerobic zone and the sulfate reduction zone, a surprisingly sharp decrease of ORP from a positive potential of +194 mV to a negative potential of -77 mV was observed. This occurred within a narrow band of 50 microm in depth. These new experimental findings support the concept of stratification of microbial processes and the associated ORP change in biofilms.

Azo Compounds↗
PubMedDate not supplied

Analysis of the degree of conversion of LED and halogen lights using micro-Raman spectroscopy.

This study determined the degree of conversion of two LED (light-emitting diodes) (Elipar FreeLight [FL], 3M ESPE; GC e-Light [EL], GC), a high intensity (Elipar TriLight [TL], 3M ESPE) and a very high intensity (Astralis 10 [AS], Ivoclar Vivadent) halogen light. The degree of conversion of these lights was compared to a conventional halogen light (Max [MX] (control), Dentsply-Caulk). Ten different light curing regimens, including pulse (EL1), continuous (FL1, EL2, TL1), turbo (EL3, AS1) and soft-start (FL2, EL4, TL2) modes of various lights were also investigated. Composite specimens of dimensions 3 x 3 x 2 mm were cured with the 10 different light curing regimens investigated. Micro-Raman spectroscopy was used to determine the degree of conversion at the top and bottom surfaces of a composite restorative (Z100, [3M ESPE]) at 60 minutes post-light polymerization. Five specimens were made for each cure mode. The results were analyzed using ANOVA/Scheffe's post-hoc test and Independent Samples t-tests at significance level 0.05. The degree of conversion ranged from 55.98 +/- 2.50 to 59.00 +/- 2.76% for the top surface and 51.90 +/- 3.36 to 57.28 +/- 1.56% for the bottom surface. No significant difference in degree of conversion was observed for the 10 light curing regimens when compared to MX (control). The curing efficiency of LED lights was comparable to halogen lights regardless of curing modes.

Analysis of Variance↗
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↗