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Biomedical subjects

D Ash

Publications and source records attributed to D Ash.

34 records · Page 2Linked to original sources
PubMed1988

Therapeutic ratio of photodynamic therapy in the treatment of superficial tumours of skin and subcutaneous tissues in man.

Six patients with a total of 34 assessible subcutaneous or cutaneous lesions were treated with photodynamic therapy using 1.0, 1.5 or 2.0 mg kg-1 of photofrin II and 25-100 J cm-2 of red light (630 nm). The incidence of complete tumour response and skin necrosis were used to try to assess the therapeutic ratio of photodynamic therapy. The tumour response rate was 47%. The rate of tumour control and necrosis increased in parallel with dose of photosensitizer and light used, implying a low therapeutic ratio. However, the use of necrosis with eschar formation as an end-point for severe normal tissue damage is questioned as the skin healed completely in all cases and with minimal discomfort to the patients.

Dihematoporphyrin Ether↗
PubMed1986

Prosthodontists' preferences in preprosthetic surgery.

A survey of members of the Federation of Prosthodontic Organizations was done to determine their opinions about various preprosthetic surgical procedures used to treat patients with alveolar atrophy of the maxilla and mandible. In most instances there was lack of consensus, indicating a need for consultation and close cooperation between the oral and maxillofacial surgeon and the prosthodontist in the management of individual patients.

Alveolar Ridge Augmentation↗
PubMed1985

Problems associated with iridium-192 wire implants.

Three incidents are reported, from different radiotherapy centres, in which an implanted iridium-192 wire remained in the tissues of a patient after withdrawal of the plastic tubing in which it was contained. In each case the instrument used to cut the wire had probably formed a hook on the end of the wire which caused it to catch in the tissues. Detailed recommendations are made for avoiding such incidents in the future, the most important of which is that the patient should be effectively monitored after the supposed removal of all radioactive sources.

Aged↗
PubMed1982

Whooping cough.

Explore the source record for details and available documents.

Diphtheria Toxoid↗
PubMed1979

Aliphatic ketones are acetylcholinesterase inhibitors but not transition state analogs.

A number of C4--C9 aliphatic ketones are acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) inhibitors, with Ki values in the 0.7--5 mM range. Comparison to analogous substrates would suggest that these ketones are transition state analogs; e.g. 2-pentanone binds to the enzyme approx. 550 times more tightly than ethylacetate. However, a number of other criteria contradict this conclusions: (1) the binding is insensitive to ketone structure: isomeric ketones, cycloalkanones, and sterically hindered ketones have similar inhibitory potencies. (2) Analogous alcohols are also good inhibitors even though they cannot form hemiketals with the enzyme. (3) Representative ketones are relatively ineffective at blocking inactivation of the enzyme by methylsulfonyl fluoride, indicating that ketones do not bind principally at the hydrolytic site. (4) A competition experiment shows that binding of tetramethylammonium chloride excludes binding of 2-pentanone, suggesting that ketones bind to the anionic rather than the hydrolytic site. Thus, observation of tight binding relative to a substrate is not a sufficient criterion to establish that an inhibitor is a transition state analog.

Animals↗
PubMed1978

The Paris system in interstitial radiation therapy.

As a result of almost 20 years' experience using 192Ir wires in interstitial radiation therapy, a new method of dose calculation has been evolved, which is especially suitable for the techniques employed. Because this system was developed and brought into routine use in Paris, it was called the Paris System. Its basic principles are outlined in this report and the manner in which it is used in clinical practise is explained.

Breast Neoplasms↗
PubMed1977

The mode of binding of potential transition-state analogs to acetylcholinesterase.

Phenylacetone, 4-phenyl-2-butanone, and 4-oxopentyltrimethylammonium chloride were tested as potential transition state analogs for eel acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7). Phenylacetone is a competitive inhibitor of the enzyme but not a transition state analog, since its binding constant is similar to that for the substrate phenyl acetate. 4-Phenyl-2-butanone binds 6-18 times more tightly than the inhibitors 4-phenyl-2-butanol and N-benzylacetamide and the substrate benzyl acetate and also blocks inactivation of the enzyme with methanesulfonyl fluoride. However, its binding is independent of pH in the range 5-7.5, whereas both V and V/Km for benzyl acetate hydrolysis decrease with decreasing pH in this range. These data indicate a specific but weak interaction between the ketone carbonyl and the enzyme, but probably do not justify considering this compound a transition state analog. 4-oxopentyltrimethylammonium iodide has previously been shown to bind about 125 times more strongly than the substrate acetylcholamine. It also binds about 375 times more strongly than the alcohol 4-hydroxypentyltrimethylammonium iodide. Furthermore, the ketone protects the enzyme from inactivation by methansulfony fluoride, while the corresponding quaternary ammonium alcohol accelerates this inactivation reaction. This additional information confirms that the ketone is a transition state analog.

Acetone↗
PubMedDate not supplied

Evaluating cost center productivity.

The monthly and yearly productivity summaries were developed and applied to a computer spreadsheet to aid the nurse manager in better understanding and communicating budget issues for diverse ambulatory care departments. A computerized spreadsheet using a commercially available personal computer program, such as Lotus, Quattro Pro, or Excel, can be used to more quickly and accurately track and summarize monthly budget reports. The data can be entered into the spreadsheet either manually or imported by query from the financial mainframe system. Contact your agency's finance or information department for information on how to accomplish this. Periodically acuity and resources should be measured and compared with quality monitors to maintain standards. For the past 10 years, our facility has successfully used this tool to make more informed decisions by identifying trouble spots early, and taking corrective action to avoid crisis management.

Ambulatory Care↗
PubMedDate not supplied

Quality assurance in brachytherapy: the role of the ICRU in achieving uniformity in dose and volume specification for reporting.

A quality assurance programme in brachytherapy implies a general consensus on the method of dose and volume specification for reporting. This in turn implies a consensus on certain definitions of terms and concepts. For several decades, the ICRU (International Commission on Radiation Units and Measurements) has been actively involved in an effort to reach a consensus between different brachytherapy centres worldwide, and to improve uniformity in reporting. The ICRU has prepared two reports containing recommendations for reporting brachytherapy treatments. The first, report #38 published in 1985, deals with intracavitary therapy in gynecology. The second deals with interstitial therapy, and is now in press. A summary of these two ICRU reports is presented here. Some definitions of terms and concepts are first recalled and discussed: Total Reference Air Kerma (TRAK), gross tumor volume (GTV), clinical target volume (CTV), treated volume, mean central dose, dose uniformity parameters, etc. Specific recommendations for reporting interstitial and intracavitary brachytherapy are then presented.

Brachytherapy↗