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Biomedical subjects

S Yang

Publications and source records attributed to S Yang.

701 records · Page 39Linked to original sources
PubMedDate not supplied

Impact of a computer-based patient record system on data collection, knowledge organization, and reasoning.

OBJECTIVE: To assess the effects of a computer-based patient record system on human cognition. Computer-based patient record systems can be considered "cognitive artifacts," which shape the way in which health care workers obtain, organize, and reason with knowledge. DESIGN: Study 1 compared physicians' organization of clinical information in paper-based and computer-based patient records in a diabetes clinic. Study 2 extended the first study to include analysis of doctor-patient-computer interactions, which were recorded on video in their entirety. In Study 3, physicians' interactions with computer-based records were followed through interviews and automatic logging of cases entered in the computer-based patient record. RESULTS: Results indicate that exposure to the computer-based patient record was associated with changes in physicians' information gathering and reasoning strategies. Differences were found in the content and organization of information, with paper records having a narrative structure, while the computer-based records were organized into discrete items of information. The differences in knowledge organization had an effect on data gathering strategies, where the nature of doctor-patient dialogue was influenced by the structure of the computer-based patient record system. CONCLUSION: Technology has a profound influence in shaping cognitive behavior, and the potential effects of cognition on technology design needs to be explored.

Cognition↗
PubMedDate not supplied

Changes in health plans serving Medicaid, 1993-1996.

To better understand the Medicaid managed care market during a period of rapid change, we developed a new data set that links Medicaid enrollment data with health maintenance organization (HMO) industry data for 1993-1996 to analyze Medicaid enrollment in full-risk health plans. Nearly half of the Medicaid enrollees in a fully capitated managed care arrangement were in plans in which Medicaid makes up at least 75 percent of the total enrollment. In addition, the number of Medicaid-only plans has more than doubled since 1993. Commercial-based plans participated increasingly in Medicaid managed care during the period, yet more than half of the plans entering the Medicaid market were newly formed.

Capitation Fee↗
PubMedDate not supplied

Monotropa uniflora plants of eastern Massachusetts form mycorrhizae with a diversity of russulacean fungi.

Plant species in the subfamily Monotropoideae are mycoheterotrophs; they obtain fixed carbon from photosynthetic plants via a shared mycorrhizal network. Previous findings show mycoheterotrophic plants exhibit a high level of specificity to their mycorrhizal fungi. In this study we explore the association of mycorrhizal fungi and Monotropa uniflora (Monotropoideae: Ericaceae) in eastern North America. We collected M. uniflora roots and nearby basidiomycete sporocarps from four sites within a 100 km2 area in eastern Massachusetts. We analyzed DNA sequences of the internal transcribed spacer region (ITS) from the fungal nuclear ribosomal gene to assess the genetic diversity of fungi associating with M. uniflora roots. In this analysis we included 20 ITS sequences from Russula sporocarps collected nearby, 44 sequences of Russula or Lactarius species from GenBank and 12 GenBank sequences of fungi isolated from M. uniflora roots in previous studies. We found that all 56 sampled M. uniflora mycorrhizal fungi were members of the Russulaceae, confirming previous research. The analysis showed that most of the diversity of mycorrhizal fungi spreads across the genus Russula. ITS sequences of the mycorrhizal fungi consisted of 20 different phylotypes: 18 of the genus Russula and two of Lactarius, based on GenBank searches. Of the sampled plants, 57% associated with only three of the 20 mycorrhizal fungi detected in roots, and of the 25 sporocarp phylotypes collected three, were associated with M. uniflora. Furthermore the results indicate that the number of different fungal phylotypes associating with M. uniflora of eastern North America is higher than that of western North America but patterns of fungal species abundance might be similar between mycorrhizae from the two locations.

Agaricales↗
PubMedDate not supplied

Pre-operative ultrasonography guiding minimal, selective surgical approach in primary hyperparathyroidism.

BACKGROUND: The traditional surgical approach for the treatment of primary hyperparathyroidism (HPT) has been routine bilateral surgical exploration. Our aim was to evaluate pre-operative ultrasonography (U/S) in altering our practice to selective unilateral neck exploration. PATIENTS AND METHODS: A retrospective study was conducted involving 53 patients who had parathyroidectomy over a 5-year period (1989-1994), 41 of whom with the diagnosis of HPT had pre-operative neck U/S. RESULTS: Thirty-eight patients had a single adenoma, one had parathyroid cancer, and two had multiple adenomas. Thirty-six of 41 (88%) patients were true positives, two (5%) false positives, two (5%) false negatives and one (2%) was true negative. Based on the surgeon's personal preference and U/S results, 21/41 (51%) of patients had bilateral and 20/41 (49%) had unilateral neck exploration. All the 41 patients had resolution of the hypercalcemia postoperatively. Eighteen of 38 (47%) patients with a single adenoma had bilateral neck exploration and only in two patients was this necessary. CONCLUSIONS: Patients undergoing parathyroid surgery for HPT should have preoperative U/S and, if a single enlarged parathyroid gland is found, unilateral U/S guided neck exploration is safe and economical. In all the other patients, bilateral exploration is the preferred approach.

Adenoma↗
PubMedDate not supplied

A bibliometric analysis of the pediatric dental literature in MEDLINE.

PURPOSE: The purpose of this study was to estimate the availability of dental literature between 1989 and 1998 in seven disciplines within pediatric dentistry by using a bibliometric analysis on MEDLINE and to compare the results to that for adolescents and adults. METHODS: A search strategy was developed for each discipline incorporating dental vocabulary obtained from the MEDLINE Medical Subject Heading (MeSH) index. The number of articles retrieved from MEDLINE for adolescents and adults (> 13 yo) was compared to those for children (< 12 yo) in seven dental disciplines: dental implants, endodontics, oral medicine/radiology, oral surgery, orthodontics, periodontics, and restorative dentistry. RESULTS: There was an average of 8,097 dental articles published each year for the combined seven disciplines studied with an eight-fold range from 327 articles/year for endodontics to 2,765 articles/year for oral medicine/radiology. Of the mean number of articles published each year, 1,273 (16%) were limited to children, while the remaining 6,824 (84%) were on adolescents and adults. The number and percentage of children articles relative to the total number of publications on children ranged from 7 articles/year (1%) for dental implants to 528 articles/year (42%) for oral medicine/radiology. Implant dentistry publications increased the fastest, growing at an average yearly rate of 25%, followed by restorative dentistry (9%), endodontics (9%), oral surgery (6%), orthodontics (6%), periodontics (3%), and oral medicine/radiology (2%). CONCLUSIONS: There is a substantial amount of literature in pediatric dentistry upon which to base clinical decisions. Within this large body of literature, there is a significant amount of variation between the various dental disciplines examined. To stay current, one would need to read and absorb approximately 24 articles each week over 52 weeks per year in more than 75 different journals. Furthermore, the volume of literature is increasing each year, making access even more difficult. These trends suggest the need for computer systems that will facilitate access and retrieval of clinically useful literature.

Adolescent↗
PubMedDate not supplied

Glucose biosensors with enzyme entrapped in polymer coating.

The pursuit of reliable biosensors for measuring glucose levels has been ongoing for decades. Their importance lies partly in the development of the implantable artificial pancrease, which can be used to deliver insulin to diabetics without the need to test glucose levels externally, with automatic delivery based on physiologic demand. Glucose sensors can also be used in short-term monitoring of glucose levels in hospitals and clinical laboratories. Three types of glucose biosensors were studied. All were based on a two-electrode system: an insulated platinum wire as a hydrogen peroxide electrode, and a silver wire twisted around the platinum wire as both a reference and a counter electrode. Each was coated with the enzyme glucose oxidase entrapped in a polymer matrix of cellulose acetate (CA) or poly 2-hydroxyethyl methacrylate (HEMA), then dip-coated by an additional polymer coating of polyvinylchloride (PVC), polyurethane (PU), or HEMA. The experiments were designed mainly to study the effectiveness of polymer coatings as diffusion-limiting membranes. The effect of each coating on the linear response to glucose concentration was examined. It was shown that additional (multiple) coatings can increase the linearity of the sensor response. The best results were obtained when the sensor was PVC-dip-coated three times. This preparation had a linear response up to 600 mg/DL glucose concentration. The sensors coated with PU and HEMA have linearity up to 280 and 240 mg/DL glucose concentrations, respectively. It was also shown that the coatings reduce interference from certain body chemicals.

Biocompatible Materials↗
PubMedDate not supplied

Cloning of a partial length cDNA encoding the C-terminal portion of the 75-77-kDa antigen of Trypanosoma cruzi.

It has been suggested that several Trypanosoma cruzi antigens have possible protective epitopes which may be suitable vaccine candidates. We found previously that animals resistant to T. cruzi infection produced antibodies against the 75-77-kDa parasite antigen. To test the ability of the recombinant form of this antigen to protect animals from T. cruzi infection, the cDNA which encodes a portion of the 75-77-kDa antigen was cloned using a cDNA library constructed in an orientation-specific bacteriophage expression vector (lambda gt 11) from poly (A)+ RNA of Brazil strain epimastigotes. One clone, named SFS-40, was selected by screening the library using affinity purified antibodies specific for the 75-77-kDa parasite antigen as probe. The cDNA corresponding to the 1.7-kilobase insert of SFS-40 was subcloned into plasmid vectors and characterized. The cDNA sequence encodes a polypeptide of about 40 kDa. The putative product of the cDNA was homologous to members of the 70-kDa stress protein family. When epimastigotes were shifted from 29 degrees C to 37 degrees C, there was no change in the level of SFS-40 mRNA. In contrast, the 70-kDa heat shock protein mRNA of the parasite was increased about four fold by this treatment.

Amino Acid Sequence↗
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Inducibility of enzyme activities associated with the cytochrome P-450 1A family, ethoxyresorufin O-deethylase, and methoxyresorufin O-demethylase in human hepatocyte lines derived from normal liver tissue.

Three human hepatocyte cultures have been developed from specimens of normal human liver, in each case from an infant or child, by coculture with liver epithelial cells from 6-day-old rat pups in a complex growth medium. In the established cultures hepatocytes predominate and maintain typical hepatocellular morphology by light microscopy and albumin secretion into supernatant medium. The activity of ethoxyresorufin O-deethylase (EROD) and methoxyresorufin O-demethylase (MROD) basally and after treatment with polycyclic aromatic hydrocarbons was measured spectrofluorometrically in cell homogenates from each culture. Very low levels of EROD and MROD activity were found in each culture without induction [EROD: 1.78 +/- 0.71 (mean +/- SE) pmol/min/mg protein; MROD: 1.33 +/- 0.10 pmol/min/mg protein]. After treatment with 10 microM dibenz (a,h)anthracene x 48 hr, EROD and MROD activities rose approximately 20- to 50-fold. When the basal and induced enzyme activities were remeasured 2 months later, results were essentially the same. Incubation with 10 microM benz(a)anthracene x 48 hr also led to induction of EROD and MROD activities. We believe that these cultures can be regarded as human hepatocyte lines, which conserve human hepatic polycyclic aromatic hydrocarbon-inducible P-450s, most likely including P-450 1A2.

Adolescent↗
PubMedDate not supplied

Increasing the yield of Eimeria tenella oocysts in primary chicken kidney cells.

The present study was undertaken to increase the yield of Eimeria tenella oocysts in primary chicken kidney cells (PCKCs) using a comparatively inexpensive cell-culture system. PCKCs growing on coverslips positioned on the bottoms of individual wells in 24-well tissue-culture plates were infected with sporozoites of E. tenella. The effects of changing the culture medium (RPMI 1640), medium pH, serum type, and serum concentration in the wells were determined by counting newly produced oocysts at 7 days postinoculation. There were significantly more (P < 0.01) oocysts produced when the medium was supplemented with 10% fetal bovine serum (FBS) and changed either daily or every other day compared with not changing the medium. When the same medium was changed daily, significantly more (P < 0.05) oocysts were produced at pH 7.4 than at pH 8.0 but not at pH 6.0. If the medium was changed daily, significantly more (P < 0.05) oocysts were produced when medium was supplemented with 10% FBS only rather than 5% and 10% chicken serum. The cell-culture system described in this study offers a convenient and efficient method for investigating the biological, biochemical, and immunological relationships between E. tenella and the host cell.

Animals↗
PubMedDate not supplied

A glucose biosensor based on an oxygen electrode: in-vitro performances in model buffer solution and in blood plasma.

An implantable biosensor for continuous monitoring of glucose levels in diabetic patients was developed. The biosensor is based on an amperometric oxygen electrode and glucose oxidase immobilized on carbon powder held in the form of a liquid suspension. The enzyme material can be replaced (the sensor recharged) without sensor disassembly. Sensors with polycarbonate glucose-diffusion membranes coated with silastic were studied. Calibration curves of the sensors in phosphate buffer solution and in undiluted blood plasma at body temperature were obtained and compared. Sensors were tested for long-term performance in vitro in model phosphate buffer solution and in blood plasma at room and at body temperature. Reproducibility of the sensor responses in plasma at body temperature was demonstrated. During continuous operation at body temperature, the sensors have a lifetime of at least six weeks.

Biomedical Engineering↗
PubMedDate not supplied

Adapting Eimeria tenella to grow in primary chicken kidney cells following repeated passages between cell culture and chickens.

The present study was undertaken to adapt a field isolate (F0) of Eimeria tenella to grow in primary chicken kidney cells (PCKCs) by selecting for characteristics of the parasite rather than modifying the culture and/or environmental conditions. Fourteen generations (F1 to F14) of E. tenella were produced following repeated passages between PCKCs and chickens. Although F1 yielded only a 28% increase in oocysts, in PCKCs compared with F0, F2 to F5 produced from 259% to 277% more oocysts, respectively. There was no significant increase in the percentage of oocysts produced in PCKCs by F6 to F14 compared with F5. Generations F1 to F14 demonstrated a greater propensity for multiple infections within the same host cell than did F0. For example, it was not uncommon to observe two, three, and occasionally four oocysts within a single PCKC. Chickens inoculated with F0 oocysts generally experienced greater pathogenesis by day 7 postinoculation than chickens inoculated with F14 oocysts as measured by decreased body weights, increased cecal lesions, and a higher mortality rate.

Animals↗