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Biomedical subjects

J C Yang

Publications and source records attributed to J C Yang.

At least 235 records · Page 13Linked to original sources
PubMed1975

The diposi tion of morphine in surgical patients.

The disposition of serum morphine following administration of 10 mg/70 kg was determined by a sensitive and specific radioimmunoassay in 31 anethetized surgical patients ranging in age from 23 to 75 yr. Following iv injection, 93 per cent of the morphine disappeared from the serum within 5 min. The early serum levels of the drug (2 min) correlated directly with the patients' ages (r equal to 0.63, p smaller than 0.01). Patient 23 to 50 yr of age averaged 0.29 mug/ml, whereas patients 51 to 75 ur of age averaged 70 percent higher, 0.49 mug/ml. The serum half-life between 10 and 240 min was independent of age and averaged about 2 hr after either iv or im administration. Following im admininstration, morphine was rapidly absorbed, with peak levels occurring within 10 to 20 min. The decline in morphine serum levels paralleled the decline in morphine analgesia and was coincident with the apperance of morphine glucuronide in the serum. These studies demonstrate the applicability and specificity of the radioimmunoassay for morphine and suggest that serum levels of morphine may be a useful and objective indicator of its pharmacologic activity.

Adult↗
PubMed1975

Stereoisomeric Characterization of Tartaric Acid Produced during l-Ascorbic Acid Metabolism in Plants.

Labeled tartaric acids from Pelargonium crispum apices which had been fed l-ascorbic acid-6-(14)C and Vitis labrusca and Parthenocissus inserta tissues which had been fed l-ascorbic acid-1-(14)C were examined by chemical means to determine chiral configuration. In each instance, label was associated with (+)-tartaric acid.Similar experiments with labeled tartaric acid from P. crispum which had been labeled with d-glucose-1-(14)C or -6-(14)C led to the same result. No evidence was obtained for formation of labeled meso-tartaric acid in experiments described above. The recent suggestion of H. Ruffner and D. Rast (Z. Pflanzenphysiol. 73: 45-55, 1974) that conversion of l-ascorbic acid to tartaric acid in plants is a nonenzymatic process is re-examined in the light of present findings.

Journal Article↗
PubMed1975

Metabolic Conversion of l-Ascorbic Acid to Oxalic Acid in Oxalate-accumulating Plants.

l-Ascorbic acid-1-(14)C and its oxidation product, dehydro-l-ascorbic acid, produced labeled oxalic acid in oxalate-accumulating plants such as spinach seedlings (Spinacia oleracea) and the detached leaves of woodsorrel (Oxalis stricta and O. oregana), shamrock (Oxalis adenopylla), and begonia (Begonia evansiana). In O. oregana, conversion occurred equally well in the presence or absence of light. This relationship between l-ascorbic acid metabolism and oxalic acid formation must be given careful consideration in attempts to explain oxalic accumulation in plants.

Journal Article↗
PubMed1974

Acupunctural analgesia? Evaluation by signal detection theory.

Pain responses to noxious thermal stimulation decreased in the acupunctured arm of subjects as compared to the arm not treated with acupuncture; this result suggested that effective analgesia had been induced. However, sensory decision theory analysis of the data revealed no difference in discriminability. This failure to find a sensory (physiological) change strongly suggests that analgesia had not been induced. The sole effect of acupuncture was to cause the subjects to raise their pain criterion in response to the expectation that acture works.

Acupuncture Therapy↗
PubMedDate not supplied

A statewide study of academic variables affecting performance of baccalaureate nursing graduates on licensure examination.

The purpose of this study was to validate, using a statewide sample, findings from two previous smaller studies investigating the relationships between admission selection variables and subsequent achievement in baccalaureate nursing programs and performance on the National Council Licensure Examination for Registered Nurses (NCLEX-RN). Subjects for this study were 1,069 graduates of nine Iowa basic baccalaureate nursing programs. The analyses included three major components. The first addressed the relationship between admission selection variables and subsequent achievement in the nursing programs and performance on a standardized nursing achievement test (AssessTest) and the NCLEX-RN. The second component investigated the extent to which achievement in nursing courses predicted performance on the NCLEX-RN. In the third component a path analysis was used to formulate a causal model describing the relationships among the variables in the study. The results of the study suggest that students' prenursing grade point average and American College Testing scores predict their performance on the NCLEX-RN. Knowledge of performance predictors can both facilitate admission selection and the use of educational resources to develop nursing competence and promote success in obtaining licensure to practice.

Achievement↗
PubMedDate not supplied

The validity of ACT-PEP test scores for predicting academic performance of registered nurses in BSN programs.

This study investigated the validity of three American College Testing-Proficiency Examination Program (ACT-PEP) tests (Maternal and Child Nursing, Psychiatric/Mental Health Nursing, Adult Nursing) for predicting the academic performance of registered nurses (RNs) enrolled in bachelor's degree BSN programs nationwide. This study also examined RN students' performance on the ACT-PEP tests by their demographic characteristics: student's age, sex, race, student status (full- or part-time), and employment status (full- or part-time). The total sample for the three tests comprised 2,600 students from eight institutions nationwide. The median correlation coefficients between the three ACT-PEP tests and the semester grade point averages ranged from .36 to .56. Median correlation coefficients increased over time, supporting the stability of ACT-PEP test scores for predicting academic performance over time. The relative importance of selected independent variables for predicting academic performance was also examined; the most important variable for predicting academic performance was typically the ACT-PEP test score. Across the institutions, student demographic characteristics did not contribute significantly to explaining academic performance, over and above ACT-PEP scores.

Education, Nursing, Baccalaureate↗
PubMedDate not supplied

The envelope protein of an endogenous murine retrovirus is a tumor-associated T-cell antigen for multiple murine tumors.

Recently, significant progress has been made in identifying specific tumor-associated antigens recognized by T cells and defining the specific peptide epitopes within these proteins that are processed and presented on class I major histocompatibility antigens. Most of these antigens have been identified in human melanoma, where many of them appear to be tissue-specific, nonmutated proteins expressed by melanoma and normal melanocytes but not by other tissues. There has been much less progress in identifying the tumor antigens on murine tumors that are recognized by T cells, and this has restricted the development of preclinical animal models for immunotherapy. The authors previously described a method for generating tumor-reactive T cells from murine tumors (tumor infiltrating lymphocytes) that are CD8+ T cells recognizing autologous tumor and that can inhibit established tumor on adoptive transfer. Here the authors show that the envelope protein of an endogenous murine retrovirus of the AKV family, found in the germline of the C57BL/6 mouse, is recognized by tumor-infiltrating lymphocytes from two histologically different tumors syngeneic to that mouse strain. Furthermore, the authors identify the specific 9-amino acid peptide from the p15E transmembrane component of this envelope protein that is recognized in the context of major histocompatibility complex Kb, show that it is naturally presented and recognized on several other H-2b tumors, and that cytotoxic T lymphocytes specific for this epitope are therapeutic for these antigen-expressing tumors on adoptive transfer.

Animals↗
PubMedDate not supplied

Adoptive transfer of cloned melanoma-reactive T lymphocytes for the treatment of patients with metastatic melanoma.

This report describes a phase I study of the adoptive transfer of cloned melanoma antigen-specific T lymphocytes for therapy of patients with advanced melanoma. Clones were derived from peripheral blood lymphocytes or tumor-infiltrating lymphocytes of patients who had received prior immunization with the melanoma-associated antigen, gpl00. In response to its cognate antigen, each clone used for treatment secreted large amounts of interferon-gamma and granulocyte-macrophage colony-stimulating factor, lesser amounts of interleukin (IL)-2 and tumor necrosis factor-alpha, and little or no IL-4 and IL-10. Clones also demonstrated recognition of human leukocyte antigen-matched melanomas using cytokine secretion and lysis assays. Twelve patients received 2 cycles of cells alone; 11 patients received additional cycles of cells and were randomized between two schedules of IL-2 (125,000 IU/kg subcutaneously daily for 12 days versus 720,000 IU/kg intravenously every 8 h for 4 days). A total of 51 cycles of cells were administered, with an average of 1 x 10(10) cells per cycle. Peripheral blood samples were analyzed for persistence of transferred cells by T-cell receptor-specific polymerase chain reaction. Transferred cells reached a maximum level at 1 h after transfer but rapidly declined to undetectable levels by 2 weeks. One minor response and one mixed response were observed (both in the high-dose IL-2 arm). This report demonstrates the safety and feasibility of cloned T-cell transfer as a therapy for patients with cancer. The lack of clinical effectiveness of this protocol suggests that transfer of different or additional cell types or that modulation of the recipient host environment is required for successful therapy.

Adult↗
PubMedDate not supplied

Development of infection resistant polyurethane biomaterials using textile dyeing technology.

Infection is a major complication when using biomaterials such as polyurethane in the clinical setting. The purpose of this study was to develop a novel infection resistant polyurethane biomaterial using textile dyeing technology. This procedure results in incorporation of the antibiotic into the polymer, resulting in a slow, sustained release of antibiotic from the material over time, without the use of exogenous binder agents. Polycarbonate based urethanes were synthesized that contained either a non-ionic (bdPU) or anionic (cPU) chain extender within the polymer backbone and cast into films. The fluoroquinolone antibiotic ciprofloxacin (Cipro) was applied to bdPU and cPU using textile dyeing technology, with Cipro uptake determined by absorbance reduction of the "dyebath." These dyed bdPU/cPU samples were then evaluated for prolonged Cipro release and antimicrobial activity by means of spectrophotometric and zone of inhibition assays, respectively. Cipro release and antimicrobial activity by dyed cPU segments that were aggressively washed persisted over 9 days, compared with dyed bdPU and dipped cPU control segments that lasted < 24 hours. Dyed cPU segments, which remained in a static wash solution, maintained antimicrobial activity for 11 days (length of study), whereas controls again lost antimicrobial activity within 24 hours. Thus, application of Cipro to the cPU polymer by means of dyeing technology results in a slow sustained release of antibiotic with persistent bacteriocidal properties over extended periods of time.

Anti-Infective Agents↗
PubMedDate not supplied

Thermal sensory decision theory indices and pain threshold in chronic pain patients and healthy volunteers.

Fifty-five low back pain patients and 47 healthy volunteers judged the intensity of calibrated thermal stimuli. The method of constant stimuli yielded a pain threshold, and sensory decision theory (SDT) methods provided two independent indices of perceptual performance: discriminability, P(A), the ability to differentiate among various stimulus intensities; and report criterion, B, the tendency to use a particular response. Compared to healthy volunteers, chronic pain patients were far poorer discriminators [lower P(A)]. In addition, the chronic pain patients were more stoical (higher B) and had higher thresholds for reporting both very faint pain and pain. The poor discriminability in patients could be due to attenuation of afferent neural input. The higher criterion suggests that the thermal stimuli were perceived as being innocuous relative to their clinical pain. Comparison of SDT indices with the threshold measures revealed that the pain threshold was highly correlated to the subject's criterion for reporting pain, B, and unrelated to discriminability, P(A).

Adaptation, Physiological↗
PubMedDate not supplied

Effects of halothane, pentobarbital and ketamine on serum melatonin levels in the early scotophase in New Zealand white rabbits.

In mammals, the nocturnal rise in pineal melatonin is regulated by signals from the endogenous clock, the hypothalamic suprachiasmatic nuclei. There have been few reports on whether anaesthetics which modulate multisynaptic neuronal functions affect melatonin secretion. We studied the effects of three commonly used anaesthetics, halothane, pentobarbital and ketamine, on serum melatonin levels in male New Zealand white rabbits. Seven blood samples were collected, 30-60 min apart, before, during and after anaesthesia. Experiments were performed in the late light and early dark period, so that changes in melatonin secretion would be reflected in the onset and/or level of nocturnal serum melatonin. Serum melatonin levels were determined by radioimmunoassay. Our results indicated that halothane attenuated the release of melatonin and pentobarbital had no apparent effect, whereas ketamine potentiated the release of melatonin. These findings suggest that melatonin levels may be affected in patients anaesthetized with halothane or ketamine, resulting in disturbed biological rhythms, especially the sleep-wake cycle following recovery.

Anesthetics, Inhalation↗
PubMedDate not supplied

Effect of ethylene-vinyl acetate concentration on ethylcellulose-walled microcapsules: preparation and release kinetics of theophylline microcapsules.

The effect of concentration of ethylene-vinyl acetate (EVA) copolymer, used as a coacervation-inducing agent, on the preparation of ethylcellulose microcapsules was studied with theophylline as the core material. The influence of EVA concentration on the micromeritic properties of the microcapsules and their drug release behaviour were investigated. Particle size distribution of the microcapsules obtained was dependent on the amount of EVA copolymer. As the EVA concentration increased the quantity of larger particles was reduced and that of the smaller particles was increased. Thus EVA might be used as a protective colloid to prevent aggregation of the microcapsules. The porosity of the microcapsules decreased with respect to EVA concentration, but the wall thickness of the microcapsules showed a corresponding increase. Zero-order release kinetics, from the resulting microcapsules in the initial dissolution phase was obtained. The apparent zero-order release rate in the initial steady-state decreased with the increase of EVA concentration, but T50 increased. The higher concentration of EVA causing a thick, compact wall lead to an effective prolongation of drug release.

Cellulose↗