Search PubMed⌕ Search

Biomedical subjects

S Yeh

Publications and source records attributed to S Yeh.

At least 55 records · Page 3Linked to original sources
PubMed1996

Factors influencing hepatocyte trafficking during allogeneic hepatocyte transplantation: improved liver sequestration with isolated perfusion.

Transplantation of normal or ex vivo modified hepatocytes holds promise in therapy of a variety of diseases. In order to investigate hepatocyte trafficking, and specifically to determine whether the route, method of delivery, or other host factors may affect hepatocyte sequestration in the liver, 51chromium- and 111indium-labeled hepatocytes were transplanted into allogeneic hosts. Systemic injection of hepatocytes into the femoral vein resulted in sequestration mainly in the lungs (30 +/- 4%) whereas sequestration in the liver amounted to only 5 +/- 1%. Portal injection resulted in a dramatic increase in the liver sequestration (52 +/- 4%) and a reduction in the lung (2 +/- 1%, P < 0.05 vs systemic injection). Nevertheless, nearly half of portally injected hepatocytes came to rest in other organ sites. Partial hepatectomy prior to transplantation did not change the total hepatocyte sequestration in the liver or the organ specific activity. A remote site of inflammation, in the form of a turpentine abscess, also did not alter the pattern of hepatocyte trafficking. Isolated perfusion of the liver with labeled hepatocyte, however, significantly increased the sequestration of hepatocytes at this organ (control, 52 +/- 4%; isolated perfusion, 71 +/- 9%; P < 0.05). In the delivery of potentially toxic gene products for therapy, isolated perfusion of the target organ appears to provide the greatest likelihood of restricting expression of potentially toxic gene products to the target organ.

Animals↗
PubMed1996

Cloning and characterization of a specific coactivator, ARA70, for the androgen receptor in human prostate cells.

The androgen receptor (AR) is a member of the steroid receptor superfamily that plays an important role in male sexual differentiation and prostate cell proliferation. Mutations or abnormal expression of AR in prostate cancer can play a key role in the process that changes prostate cancer from androgen-dependent to an androgen-independent stage. Using a yeast two-hybrid system, we were able to isolate a ligand-dependent AR-associated protein (ARA70), which functions as an activator to enhance AR transcriptional activity 10-fold in the presence of 10(-10) M dihydrotestosterone or 10(-9) M testosterone, but not 10(-6) M hydroxyflutamide in human prostate cancer DU145 cells. Our data further indicated that ARA70 Will only slightly induce the transcriptional activity of other steroid receptors such as estrogen receptor, glucocorticoid receptor, and progesterone receptor in DU145 cells. Together, these data suggest that AR may need a specific coactivator(s) such as ARA70 for optimal androgen activity.

Amino Acid Sequence↗
PubMed1996

Erythromycin stimulates gastric emptying after esophagectomy with gastric replacement: a randomized clinical trial.

UNLABELLED: Delayed gastric emptying after esophagogastrectomy can pose a significant early postoperative problem. Because erythromycin, which stimulates the gastric antral and duodenal motilin receptor, has been shown to significantly increase gastric emptying in patients with diabetic gastroparesis, we decided to evaluate its effect on gastric emptying after esophagogastrectomy. METHODS: Twenty-four patients (18 men and six women, age range 41 to 79 years, median 66 years) were randomized to receive either erythromycin lactobionate (200 mg in 50 ml normal saline solution intravenously) (n = 13) or placebo (50 ml normal saline solution intravenously (n = 11) 11 days after esophagogastrectomy (with pyloric drainage procedure). After erythromycin or placebo had been infused over a 15-minute period, patients ingested a solid meal (scrambled egg with bread) labeled with technetium 99m sulfur colloid (500 microCi) over approximately 15 minutes. Dynamic images of the stomach were then acquired over 90 minutes in the supine position by gamma imaging. Results were expressed as percentage of counts retained in the stomach (percent gastric retention) over time. RESULTS: There were no side effects of erythromycin. In the placebo group, the mean percent of radiolabeled meal retained in the stomach after 90 minutes was 88%, which was significantly greater than in the erythromycin group, 37% (p < 0.001). In addition, analysis of covariance demonstrated that the rate of gastric emptying (slope of the line) was significantly greater in the erythromycin-treated group than in the placebo group (p < 0.0001). CONCLUSION: Early satiety after esophagogastrectomy may be due to delayed gastric emptying and not due to a decrease in the gastric reservoir. Intravenous erythromycin significantly improves gastric emptying in patients after esophagogastrectomy by stimulating gastric motility.

Adult↗
PubMed1995

Androgen receptor: an overview.

The action of androgens in regulating development and growth is mediated by androgen receptor (AR). AR is a member of the steroid hormone receptor superfamily, a class of receptors that function through their ability to regulate the transcription of specific genes. The AR is located in various target tissues, with its levels and activity altered with the onset of various cellular events (e.g., sexual development, malignant transformation). The modulation of AR levels occurs through a number of mechanisms, including transcription, and is regulated by various factors (e.g., androgens). The ability of AR to modulate gene transcription is through its interaction with specific DNA sequences located near or within the target gene promoter. The importance of the AR in reproductive physiology has been emphasized by the finding of AR mutations, leading to a variety of disorders, including testicular feminization syndrome. In this article, we review the structure and function of AR and the role AR plays in the function of the mammalian system.

Animals↗
PubMed1994

Human and rat TR4 orphan receptors specify a subclass of the steroid receptor superfamily.

We have identified a member of the steroid receptor superfamily and cloned it from human and rat hypothalamus, prostate, and testis cDNA libraries. The open reading frame between first ATG and terminator TGA can encode 615 (human) and 596 (rat) amino acids with calculated molecular mass of 67.3 (human) and 65.4 (rat) kDa. The amino acid sequence of this protein, called TR4 orphan receptor, is closely related to the previously identified TR2 orphan receptor. The high homology between TR2 and TR4 orphan receptor suggests that these two orphan receptors constitute a unique subfamily within the steroid receptor superfamily. These two orphan receptors are differentially expressed in rat tissues. Unlike TR2 orphan receptors, the TR4 orphan receptor appears to be predominantly located in granule cells of the hippocampus and the cerebellum, suggesting that it may play some role(s) in transcriptional regulation in these neurons.

Amino Acid Sequence↗
PubMed1994

Highly effective induction therapy for stage 4 neuroblastoma in children over 1 year of age.

PURPOSE: To test the efficacy of a protocol for poor-risk neuroblastoma that builds on the following: (1) our favorable previously reported results with dose-intensive use of cyclophosphamide; (2) our retrospective analysis of neuroblastoma chemotherapy reports, which supported the value of high-dose cisplatin and etoposide (VP-16); and (3) the Goldie-Coldman hypothesis that rapid cytoreduction plus the use of non-cross-resistant chemotherapy combinations will decrease the risk of drug resistance. PATIENTS AND METHODS: The N6 protocol included seven courses of high-dose chemotherapy plus surgical resection of bulk disease. Courses 1, 2, 4, and 6 consisted of 6-hour intravenous infusions of cyclophosphamide 70 mg/kg/d on days 1 and 2 (ie, 140 mg/kg per course), a 72-hour intravenous infusion of doxorubicin 75 mg/m2 and vincristine 0.1 mg/kg beginning day 1, and vincristine 1.5 mg/m2 intravenous bolus on day 9. Courses 3, 5, and 7 consisted of 2-hour intravenous infusions of VP-16 200 mg/m2/d on days 1 to 3 (ie, 600 mg/m2 per course), and 1-hour intravenous infusions of cisplatin 50 mg/m2/d on days 1 to 4 (ie, 200 mg/m2 per course). Courses were to start after neutrophil counts reached 500/microL and platelet counts reached 100,000/microL. Response was defined by international criteria. RESULTS: Among 24 consecutive previously untreated patients diagnosed with stage 4 neuroblastoma at more than 1 year of age, 21 patients achieved a complete or very good partial remission; one patient had no evidence of disease except by iodine-131-metaiodobenzylguanidine (MIBG) scan, which was markedly improved; and one patient had resolution of extensive metastatic disease, but still had an incompletely resected primary tumor. The sole patient to have a poor response had clinical features at diagnosis that are atypical for neuroblastoma, namely, 8 years of age and an unknown primary tumor. Severe toxicities included myelosuppression, mucositis, and hearing deficits. CONCLUSION: The N6 approach reliably achieves significant cytoreduction against stage 4 neuroblastoma. This may eventuate in an improved cure rate, since consolidative treatments using myeloablative therapy, immunotherapy, or biologic response modifiers such as cis-retinoic acid are most likely to be effective against minimal residual disease.

Abdominal Neoplasms↗
PubMed1994

Image analysis of the distribution of intraperitoneally administered fluids in patients with ovarian cancer.

Patients are selected for intraperitoneal chemotherapy based on the condition of the peritoneal cavity and the volume of residual disease, as determined by second-look surgery. Several techniques have been described to assess the distribution of intraperitoneal fluids. They rely on point, as opposed to area, measurements. We performed serial radionuclide scans of 15 patients undergoing intraperitoneal chemo for ovarian cancer. Scans were performed following intraperitoneal administration of 500-1000 ml of 99Tc-labeled human serum albumin in normal saline. Each patient underwent three scans at least 4 weeks apart. Radionuclide scans were digitized for computerized analysis. Area in picture elements (pixels) and optical density (mass) of the 99Tc-labeled regions were determined and analyzed for similarities in the pattern of distribution. Area analysis was used to divide the patients into two groups. Group 2 patients (n = 7) had more patients with < 0.5 cm of residual disease (P = .051) and no evidence of disease (P = 0.1) compared with group 1 patients (n = 8). No differences in overall survival were found (P = 0.21). No objective measurement of distribution of intraperitoneally administered fluids exists. Computer image analysis may be an improvement over static scoring techniques to assess non-invasive imaging studies.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Impact evaluation of Drug Abuse Resistance Education (DARE).

The purpose of this study was to assess the impact of Drug Abuse Resistance Education (DARE) on fifth-grade students in the Long Beach Unified School District in Long Beach, California. The research suggests that DARE does not significantly change the amount of drug use, which is minimal at the fifth grade level. In general, children receiving DARE during the study period maintained existing levels of drug abuse. Approximately 3,000 students participated in the study. A pretest and posttest self-report survey was utilized during the Fall 1989 semester for experimental and control groups. As DARE programs gain popularity in other school districts, school administrators need more information on the program to decide if DARE should be presented in their schools. Administrative decision-making must consider program effectiveness and curriculum time constraints.

Child↗
PubMed1992

Therapeutic alternatives for hormone-refractory prostatic cancer.

The currently available prognostic factors allow the identification of patients who are destined to do poorly with primary hormone therapy. Standardization of these factors is required so that they become incorporated into routine practice. For patients who relapse in osseous sites radiolabeled diphosphonates are one therapeutic alternative that can provide palliation. Future use will be directed to optimize treatment schedules, and use earlier in the course of the disease so that more durable palliation of bony metastases can be achieved. Evolving data on the use of PSA show that elevations antedate clinical relapse for most patients. In these cases, sequential changes can be used to assess therapeutic effects, which in turn can allow novel therapies to be screened more rapidly in the clinic. Criteria for the degree of change that is indicative of response must be standardized. Preliminary data suggest a 50% decline be the minimum that is used. The results with agents such as suramin, which interrupts autocrine and paracrine growth factor loops, are a therapeutic strategy that need further study. Future efforts will focus on defining which patients are best suited for specific therapeutic approaches.

Antigens, Neoplasm↗
PubMed1991

Hepatic clearance and biliary secretory rate maximum of taurocholate in the recirculating and single pass isolated perfused rat liver. Effects of the cholestatic agent, estradiol-17 beta-(beta-D-glucuronide).

The ability of the cholestatic steroid glucuronide, estradiol-17 beta-(beta-D-glucuronide) (E(2)17G), to inhibit the hepatic clearance (ClH) and biliary secretory rate maximum (SRm) of taurocholate was investigated in the recirculating and single pass isolated perfused male rat liver. In the recirculating perfused liver, E(2)17G (0, 2, 4, or 6 mumol) was added as a bolus dose to the reservoir at zero time while taurocholate was infused into the portal vein in increasing amounts (15, 30, 45, or 60 mumol/mL; 1 mL/hr for 15 min each). E(2)17G (4 mumol) caused a significant (P less than 0.05) inhibition of bile flow and bile acid secretion at 10-15 min during infusion of 15 mumol/hr taurocholate but did not inhibit the SRm which occurred at 42 min, indicating that E(2)17G had not caused an irreversible inhibition of taurocholate transport. E(2)17G (6 mumol) caused a profound and irreversible inhibition of bile flow attributable to retention of E(2)17G in the liver. The noncholestatic estradiol-3-(beta-D-glucuronide) (E(2)3G; 6 mumol) had no significant effect on bile flow or the SRm. In the single pass perfused liver (10 mL/min flow rate), E(2)17G (0, 1, 2, 5, or 10 nmol/mL) or E(2)3G (2 nmol/mL) was added to the perfusate resulting in a stable infusion to the liver. [3H]Taurocholate was infused into the portal vein in increasing amounts to give inflow concentrations (Cin) of 25, 50, 75 or 100 nmol/mL. In the absence of E(2)17G, taurocholate ClH decreased from 0.92 to 0.70 mL/min/g liver with increasing taurocholate concentrations. Neither E(2)17G nor E(2)3G altered the ClH of 25 nmol/mL taurocholate. E(2)17G (10 nmol/mL) inhibited bile flow and bile acid secretion first at 20-25 min, followed by inhibition of ClH of 75 and 100 nmol/mL taurocholate (35-60 min). In contrast, E(2)3G stimulated bile acid secretion and increased the SRm by 80%. Thus, at doses that did not block its own elimination, E(2)17G did not cause an irreversible inhibition of taurocholate transport into bile. E(2)17G did not directly inhibit the uptake of taurocholate into the liver but first inhibited the biliary excretion of taurocholate, resulting in its intrahepatic accumulation and decreased clearance from the perfusate.

Animals↗
PubMed1987

Localization of radioiodinated monoclonal antibody in colorectal cancer. Initial dosimetry results.

HT-29-15 is an IgG1 monoclonal antibody reacting with a neuraminidase-sensitive determinant on a cell-surface antigen (molecular weight, 200,000 daltons) present on the colon cancer cell line HT-29. HT-29-15 was selected for a tumor localization study because the antigen was shown to be present, by immunohistochemical staining, in a high percentage of primary and metastatic colorectal cancers. HT-29-15 labeled with iodine 131 was given intravenously over a dose range of 0.2 to 10.0 mg to 23 patients with colorectal cancer. No significant toxicity was seen. Imaging of hepatic metastases was successful from days 5 to 7. Analysis of tissue radioactivity by biopsy showed that the tumor-liver ratio increased from day 1 to day 7, suggesting more rapid clearance of antibody from normal tissue than from tumor. Thus, tissue biopsy specimens and scintigraphy have shown that imaging of metastatic colorectal cancer is possible with monoclonal antibody HT-29-15. Tissue biopsy specimens are essential for demonstrating specificity of localization. Scans alone provide insufficient evidence of specific localization by monoclonal antibodies. Simultaneous infusion of a nonreactive control antibody would be necessary for specific localization to be demonstrated unequivocally.

Animals↗
PubMed1987

Medical imaging in lung cancer.

The routine imaging work-up of suspected lung cancer should include posteroanterior and lateral chest radiographs and, in most cases, a computed tomographic (CT) scan of the entire thorax and adrenal glands. In asymptomatic patients with adenocarcinoma of the lung, there is justification for doing routine contrast-enhanced CT examination of the brain. Further imaging workup will be suggested by the patient's history, physical findings, and laboratory findings. Magnetic resonance imaging of the chest in patients with lung cancer is being investigated, but current studies comparing it with CT demonstrate no definite advantage at this time, with the possible exception of the lung apex in which T1 weighted thin-section coronal views are useful.

Gallium Radioisotopes↗
PubMed1987

Monoclonal antibody to an intracellular antigen images human melanoma transplants in nu/nu mice.

Mouse monoclonal antibody TA99 detects a 70-kDa pigmentation-associated glycoprotein in human melanoma cell lines. The antigen cannot be detected on the cell surface by sensitive rosetting techniques or absorption studies, nor can it be detected as a secreted product in culture fluids. Contrary to expectation, 125I-labeled TA99 specifically localized to pigmented human melanoma transplants in nu/nu mice; no localization to nonpigmented melanoma or control tumors was found. Tumor imaging was initially obscured by circulating 125I-labeled TA99 during the first 6 days after antibody injection. With clearance of 125I-labeled TA99 from the blood (half-life, 4-7 days), specific tumor images could be clearly defined by day 13. Due to the persistence of 125I-labeled TA99 at the tumor site (8.9% of the injected dose at 1 week and 4.6% at 8-10 weeks), images were obtainable for up to 10 weeks. At 8-10 weeks, the tumor/blood ratio was 10(4)-10(5), and the tumor/normal tissue ratio ranged from 10(2) to 10(5). In view of these findings, antibodies detecting intracellular antigens may have a role in tumor imaging and therapy.

Animals↗
PubMed1986

Regional isolated limb perfusion of melanoma intransit metastases using mechlorethamine (nitrogen mustard).

Forty-two patients with intransit metastases of melanoma in a limb were treated by isolated regional perfusion chemotherapy using mechlorethamine (nitrogen mustard). Group 1 (n = 12) underwent treatment at low dose, less than 0.35 mg/kg, or low temperature, less than 38 degrees C. Group 2 (n = 30) received higher doses, 0.35 to 0.6 mg/kg, plus heat at 38 degrees C to 41 degrees C. No patient had evidence of disease outside the limb at the time of perfusion. The median follow-up time was 48 months (range, 1 to 9 years). Of the 42 patients, 29 had measurable lesions that responded as follows: group 1, complete response (CR) in two of ten and partial response (PR) in none; group 2, CR in six of 19 and PR in six of 19. The combined CR and PR rate of 12 of 19 in group 2 was significantly higher than that of group 1 (P less than .05). CR lasted only 2 months in the two patients of group 1, but persisted in the six patients of Group 2, four of whom are still alive free of disease at 16, 21, 33, and 40 months. Relapse-free control of disease in the limb was achieved in 36% of the patients in group 2 at 24 months, compared with 0% in group 1 (P less than .05). An overall survival of 74% at 48 months was observed in group 2, significantly higher than that of 64% for group 1 (P less than .05). The status of the regional lymph nodes (RLN) and the number of metastases did not affect tumor response. However, 77% of RLN-negative patients survived 48 months, in contrast to only 38% of RLN-positive patients (P less than .05). One patient died postoperatively of myocardial infarction. No serious systemic toxicity developed. Two patients who underwent repeat salvage perfusions developed a reversible peripheral neuropathy in the limb. Limb function was good after treatment, and dramatically improved in patients who had advanced satellitosis that responded to treatment. These results suggest that heated limb perfusion using mechlorethamine at an adequate dose can offer long-term control of intransit metastases in approximately one third of these patients, with preservation of good limb function and possible prolongation of survival.

Adult↗
PubMed1986

Polygonal arrays of actin filaments in human lens epithelial cells. An aging study.

In order to determine the importance of lens actin filament configuration to lens accommodation, the pattern of actin filaments in the epithelium was studied in human lenses from different decades of life spanning the accommodative and non-accommodative years. Polygonal arrays of microfilaments were demonstrated in whole mounts of epithelium from normal and cataractous lenses using rhodamine phalloidin, an actin-specific, fluorescent-labeled probe. Tangential section transmission electron microscopy (TEM) studies confirmed that these arrays consist of central vertices and interconnecting filament rays, which line the apical end of each epithelial cell and appear to attach to the lateral membrane. These polygonal arrays were present in human lenses ranging from 25-94 yr of age. Measurements of intervertex distance showed remarkable constancy throughout the ages studied. In view of these findings, it is proposed that a possible function of these polygonal arrays is to stabilize the lens epithelium during lens flattening.

Actins↗