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Biomedical subjects

J K Parker

Publications and source records attributed to J K Parker.

9 recordsLinked to original sources
PubMed2001

Flavor-protein binding: disulfide interchange reactions between ovalbumin and volatile disulfides.

The irreversible binding of selected sulfur-containing flavor compounds to proteins was investigated in aqueous solutions containing ovalbumin and a mixture of disulfides (diethyl, dipropyl, dibutyl, diallyl, and 2-furfuryl methyl) using solid-phase micro-extraction (SPME). In systems which had not been heated, the recovery of disulfides from the headspace above the protein at the native pH (6.7) was similar to that from an aqueous blank. However, significant losses were observed when the pH of the solution was increased to 8.0. When the protein was denatured by heating, much greater losses were observed and some free thiols were produced. In similar heat-denatured systems at pH 2.0, no losses of disulfides were observed. Disulfides containing allyl or furfuryl groups were more reactive than saturated alkyl disulfides. Interchange reactions between protein sulfhydryl groups and the disulfides are believed to be responsible for the loss of the disulfides.

Chromatography, Liquid↗
PubMed2000

Sensory and instrumental analyses of volatiles generated during the extrusion cooking of oat flours.

Three batches of oats were extruded under four combinations of process temperature (150 or 180 degrees C) and process moisture (14. 5 and 18%). Two of the extrudates were evaluated by a sensory panel, and three were analyzed by GC-MS. Maillard reaction products, such as pyrazines, pyrroles, furans, and sulfur-containing compounds, were found in the most severely processed extrudates (high-temperature, low-moisture). These extrudates were also described by the assessors as having toasted cereal attributes. Lipid degradation products, such as alkanals, 2-alkenals, and 2, 4-alkadienals, were found at much higher levels in the extrudates of the oat flour that had been debranned. It contained lower protein and fiber levels than the others and showed increased lipase activity. Extrudates from these samples also had significantly lower levels of Maillard reaction products that correlated, in the sensory analysis, with terms such as stale oil and oatmeal. Linoleic acid was added to a fourth oat flour to simulate the result of increased lipase activity, and GC-MS analysis showed both an increase in lipid degradation products and a decrease in Maillard reaction products.

Avena↗
PubMed1999

Specialist practitioner' in surgical dentistry: preliminary report on a pilot scheme at East Surrey Hospital, Redhill, UK.

This continuing pilot scheme was designed to assess whether minor oral operations could be done by a 'specialist practitioner' in surgical dentistry in hospital. The preliminary results indicate that patients benefit from the improved facilities and expertise that are available in the hospital, that the provision of treatment within the hospital is at a sufficiently 'local' level to meet their requirements, and that this increased quality of service can be provided at no greater cost to the NHS than treating them in a dental surgery. A large amount of the dentoalveolar surgery done (such as removal of third molars) is regarded as routine, but 'routine' is often mistakenly thought to mean 'simple' or 'easy'. Dentoalveolar surgery not only demands the highest quality of care and expertise but it also requires the necessary immediate support if medical or surgical complications arise.

Adolescent↗
PubMed1995

A rapid method for the diagnosis of von Willebrand's disease subtypes by the clinical laboratory.

Von Willebrand's disease represents the most prevalent form of the inheritable bleeding disorders. Appropriate clinical management of these patients requires subtyping of the disease by examination of von Willebrand factor multimers following agarose gel electrophoresis of plasma. Previously described methods for the preparation of agarose gels in this application require extensive manipulation of the gel mold during pouring of the separating, stacking, and cathode portions of the agarose gel. We describe an improved gel mold design that expedites preparation of agarose gels by eliminating the need to disassemble the mold during preparation. In addition, using relatively inexpensive computer hardware and scanning densitometry, we have demonstrated the ability to both quantitate the von Willebrand factor antigen present and prepare a visual record of the multimer pattern for medical records.

Adult↗
PubMed1994

Characterization of prothrombin activation during cardiac surgery by hemostatic molecular markers.

BACKGROUND: Prothrombin activation represents the key regulatory step in the hemostatic process. Once formed, thrombin contributes to the generation of fibrin as well as the activation of platelets and fibrinolysis. Failure to suppress thrombin formation during cardiac surgery could result in disorders of hemostasis and thrombosis in the perioperative period. The aim of this study was to determine the time course for prothrombin activation during the perioperative period associated with cardiac surgery. METHODS: We measured prothrombin activation during the perioperative period in 19 adult patients undergoing primary cardiac surgery using enzyme-linked immunosorbent assays for the detection of thrombin formation (prothrombin fragment 1.2 and thrombin-antithrombin III complex) and thrombin activity (fibrinopeptide A and fibrin monomer). Blood samples were obtained preoperatively; at 30-min intervals during cardiopulmonary bypass (CPB); and 1, 3, and 20 h after completion of CPB. RESULTS: Despite anticoagulation with heparin, plasma concentrations of prothrombin fragment 1.2, thrombin-antithrombin III complex, and fibrin monomer increased throughout CPB. Peak concentrations for all hemostatic markers occurred in the samples obtained 3 h after completion of CPB. By the morning after surgery, plasma prothrombin fragment 1.2 returned to preoperative concentrations; however, fibrinopeptide A and fibrin monomer concentrations remained significantly increased (P < 0.05) compared to preoperative values. CONCLUSIONS: These data clearly demonstrate the occurrence of prothrombin activation and thrombin activity during CPB despite heparin concentrations adequate to maintain the activated clotting time greater than 400 s. Hemostatic markers for the activation of prothrombin demonstrated peak concentrations 3 h after completion of CPB with a return to baseline concentrations by the morning after surgery. Markers for thrombin activity, however, suggest the presence of active thrombin through the morning after surgery. Further investigations will be necessary to determine the role of hemostatic activation in thrombotic complications after cardiac surgery.

Aged↗
PubMed1986

Cross validation of some psychometric properties of the CSQ and its differential return rate as a function of token financial incentive.

The Consumer Satisfaction Questionnaire (CSQ) was developed by Larsen, Atkisson, Hargreaves, and Nguyen (1979) and has been mentioned as a possible "standard scale" for the evaluation of consumer satisfaction with mental health treatment because of its unidimensionality, reliability, validity and ease of use. A mail survey of ex-clients who had terminated treatment during the preceding year from one of six offices of a regional mental health center in the Rocky Mountain area strongly cross-validated these characteristics as well as other results from the consumer satisfaction literature. In addition, based upon evidence from marketing research, a randomly selected half of the ex-clients surveyed was offered a token inducement of two cents for returning the questionnaire while the other half was not. A significantly greater proportion of ex-clients who received the token inducement returned their questionnaires than did those who had not. This approach appears to be promising and further research with it is indicated.

Community Mental Health Centers↗