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Biomedical subjects

K W Anderson

Publications and source records attributed to K W Anderson.

47 records · Page 3Linked to original sources
PubMed1978

Computer-assisted eye examination. VII. Final evaluation of the refractor. III system for subjective examination after reducing software and hardware errors.

Eighty patient-volunteers were refracted by the computer-assisted Refractor III system and the results were compared with those obtained by the usual manual method. For the distance prescription 95% of the results were satisfactory. For the near add all were satisfactory. Relative validity of the system was also measured objectively by repeatability data. System test differences and test-retest manual-examination data were found comparable, indicating that the validity of the system is similar to that of the manual method. Further developments are expected to improve reliability, simplify maintenance, and extend testing so that the system will be an economical and useful instrument in eye clinics.

Adolescent↗
PubMed1977

Computer-assisted eye examination. V. Preliminary evaluation of the refractor III system for subjective examination.

A computer-assisted subjective eye examination was administered to 78 patients as they volunteered. They were also examined in the conventional, manual way, some before and some after the computer-assisted examination. Results of the computer-assisted examination were compared to those obtained by conventional subjective methods. For the distance prescription, satisfactory agreement was obtained for 83% of the patients. The 17% unsatisfactory prescriptions were subdivided into about 6% avoidable errors (caused by errors in software, hardware, or optometric flow charts), about 6% errors of undetermined cause, and 4% fundamental errors (caused by patient's physical and mental impairment or confusion). A similar analysis is made for the near add. With further development of the system it is expected that between 90 and 96% of patients in an optometric clinic can be successfully examined by this computer-assisted method.

Adolescent↗
PubMedDate not supplied

Treatment of head and neck melanoma, lentigo maligna subtype: a practical surgical technique.

Melanoma with the lentigo maligna histological pattern often provides a significant and difficult challenge to the head and neck surgeon. The lentigo maligna subtype is the most common type of melanoma on the head and neck. This potentially lethal form of cancer is associated with greater nonvisual lesional extension that is often not clinically apparent. Failure to excise the entire lesion results in a higher risk of local recurrence and a poorer prognosis. The staged excision technique described herein results in histological interpretation of 100% of the peripheral margins using formalin-fixed vertical sections. Definitive local excision and soft tissue reconstruction are performed in a subsequent stage, with an assurance that 100% of the peripheral margins have been evaluated and interpreted as free of disease.

Female↗
PubMedDate not supplied

Determination of the extent of protein biotinylation by fluorescence binding assay.

A method was developed to determine the total amount of biotin present in biotinylated protein conjugates. Conjugates of bovine serum albumin, alkaline phosphatase, and horseradish peroxidase were used in this case study. The extent of biotinylation was determined by complete acid hydrolysis or by enzymatic digestion using proteinase K to release biotin from the biotinylated proteins, followed by sensitive detection of biotin using a coupled HPLC-binding assay system. This detection system is based on the enhancement of the fluorescence of streptavidin-FITC by biotin. The extent of biotinylation determined by this method was compared with the values obtained by a conventional colorimetric method that is based on the displacement of the dye 4-hydroxyazobenzene-2-carboxylic acid (HABA) from the binding sites of avidin. It was found that, because the described method determines the amount of liberated biotin after hydrolysis, it does not suffer from steric hindrance problems associated with the ability of biotin on a protein surface to displace HABA from avidin. Therefore, this method can provide a more accurate determination of the extent of biotinylation. It was also determined that the acid hydrolysis of the biotinylated protein was more effective in releasing the conjugated biotin compared to enzymatic digestion by proteinase K.

Animals↗
PubMedDate not supplied

Degradation of partially oxidized alginate and its potential application for tissue engineering.

Alginate has been widely used in a variety of biomedical applications including drug delivery and cell transplantation. However, alginate itself has a very slow degradation rate, and its gels degrade in an uncontrollable manner, releasing high molecular weight strands that may have difficulty being cleared from the body. We hypothesized that the periodate oxidation of alginate, which cleaves the carbon-carbon bond of the cis-diol group in the uronate residue and alters the chain conformation, would result in promoting the hydrolysis of alginate in aqueous solutions. Alginate, oxidized to a low extent (approximately 5%), degraded with a rate depending on the pH and temperature of the solution. This polymer was still capable of being ionically cross-linked with calcium ions to form gels, which degraded within 9 days in PBS solution. Finally, the use of these degradable alginate-derived hydrogels greatly improved cartilage-like tissue formation in vivo, as compared to alginate hydrogels.

Absorbable Implants↗
PubMedDate not supplied

Controlled growth factor release from synthetic extracellular matrices.

Polymeric matrices can be used to grow new tissues and organs, and the delivery of growth factors from these matrices is one method to regenerate tissues. A problem with engineering tissues that exist in a mechanically dynamic environment, such as bone, muscle and blood vessels, is that most drug delivery systems have been designed to operate under static conditions. We thought that polymeric matrices, which release growth factors in response to mechanical signals, might provide a new approach to guide tissue formation in mechanically stressed environments. Critical design features for this type of system include the ability to undergo repeated deformation, and a reversible binding of the protein growth factors to polymeric matrices to allow for responses to repeated stimuli. Here we report a model delivery system that can respond to mechanical signalling and upregulate the release of a growth factor to promote blood vessel formation. This approach may find a number of applications, including regeneration and engineering of new tissues and more general drug-delivery applications.

Alginates↗
PubMedDate not supplied

Role of metastatic potential in the adhesion of human breast cancer cells to endothelial monolayers.

To gain further insight into the process of metastasis, adhesion to endothelial monolayers was compared for a nonmetastatic and a highly metastatic human breast cancer cell line. The parallel plate flow chamber was employed to quantify adhesion using an attachment assay. This assay was carried out at several physiological shear stresses both with and without endothelial TNF-alpha stimulation. At a venular shear stress of 1 dyne cm-2, the nonmetastatic cell line was more adhesive to stimulated endothelial monolayers, while no differences could be noted for resting monolayers. At a lower shear stress of 0.25 dynes cm-2, the highly metastatic cell line was more adhesive to stimulated endothelial monolayers, while the nonmetastatic cell line was more adhesive to resting monolayers. Thus, metastatic potential correlated with attachment only at low shear stresses and following endothelial stimulation. These results emphasize the importance of studying cancer cell adhesion under multiple physiological flow conditions. Furthermore, these results indicate that adhesion of these two cell lines may be controlled by two different mechanisms. Antibody blocking experiments of adhesion molecules on the endothelial cells confirmed that adhesion of the nonmetastatic cell line was mediated by E-selectin expressed on the endothelial cells and adhesion of the highly metastatic cell line was mediated by both E-selectin and VCAM-1 expressed on the endothelial cells.

Antibodies, Blocking↗
PubMedDate not supplied

The temporal pattern of reduction of mortality risk after smoking cessation.

We investigated the excess mortality risks of former smokers according to the number of years since they quit smoking in a cohort of 21,112 men and women evaluated with coronary angiography and included in the Coronary Artery Surgery Study registry. There is a prompt decline in mortality risk within the first year of quitting. Thereafter, former smokers have a sustained, modestly elevated mortality risk for at least 20 years compared with people who never smoked. The pattern is similar in men and women, in 35-54, 55-64, and greater than or equal to 65 age groups, and in subcohorts of those with coronary artery disease and those without coronary artery disease.

Adult↗
PubMedDate not supplied

Molecular analysis of bacterial pathogens in otitis media with effusion.

OBJECTIVE: To determine if the polymerase chain reaction (PCR) can detect bacterial DNA in pediatric middle ear effusions that are sterile by standard cultural methods. DESIGN: Single-center, blinded, comparative study of diagnostic assays. The PCR-based detection systems for Moraxella catarrhalis, Haemophilus influenzae, and Streptococcus pneumoniae were designed and validated using a battery of DNAs obtained from cultured bacteria. Chronic middle ear effusion specimens were collected and comparatively analyzed by culture and the PCR. SETTING: Tertiary care pediatric hospital. PATIENTS: A total of 97 middle ear effusions were collected from pediatric outpatients at Children's Hospital of Pittsburgh (Pa) during myringotomy and tube placement for chronic otitis media with effusion (duration > 3 months). All patients had failed multiple courses of antimicrobial therapy and were diagnosed by a combination of validated otoscopy and tympanograms. MAIN OUTCOME MEASURE: Differences in the percentage of positive test results between PCR-based assays and culture for M catarrhalis, H influenzae, and S pneumoniae. RESULTS: Of the 97 specimens of otitis media with effusion, 28 (28.9%) tested positive by both culture and PCR for M catarrhalis, H influenzae, or S pneumoniae. An additional 47 specimens (48%) were PCR positive/culture negative for these three bacterial species. Thus, 75 (77.3%) of the 97 specimens tested PCR positive for one or more of the three test organisms. The minimum number of bacterial genomic equivalents present in the average culture-negative ear was estimated to be greater than 10(4) based on dilutional experiments. CONCLUSIONS: The PCR-based assay systems can detect the presence of bacterial DNA in a significant percentage of culturally sterile middle ear effusions. While this finding is not proof of an active bacterial infectious process, the large number of bacterial genomic equivalents present in the ears is suggestive of an active process.

Bacteriological Techniques↗