Biomedical subjects
Publications and source records attributed to D Paton.
Blood samples were taken from 121 sows and gilts on 7 commercial piggeries located around Lusaka (Zambia). The samples tested negative for antibodies to Aujeszky's disease, transmissible gastroenteritis (TGE), swine influenza, hog cholera and brucellosis. Seventy-eight pigs from 5 farms had positive titres to porcine parvovirus. Eighteen sera showed positive titres to Leptospira celledoni.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
A retrospective study of patients who underwent keratoplasty for keratoconus was done in 100 consecutive cases, of which 50 were penetrating keratoplasty procedures, and 50 were lamellar keratoplasty procedures. Each case was done by the same surgeon in both series. Criteria for patient selection were essentially the same. Postoperative care differed primarily in the time before suture removal, being an average of ten months in the penetrating keratoplasty group and three months in the lamellar keratoplasty group. Of those patients who underwent penetrating keratoplasty, the mean best-corrected visual acuity was 6/6 (20/20-) and the average corneal astigmatism was + 5.00 diopters. Of those patients who received lamellar keratoplasty, the mean best-corrected visual acuity was 6/9 (20/30-), and the average corneal astigmatism was +3.25 diopters. The most frequent complications of both techniques were wound separations that responded well to resuturing.
Explore the source record for details and available documents.
The rat-liver carcinogen 4-dimethylaminoazobenzene (Butter Yellow, DAB) and 12 of its structural analogues have been evaluated in a cell transformation assay. Eight of these analogues have already been tested for carcinogenicity in rats, whilst the remaining 4 are new or hitherto untested. Benzidine and its 3,3'-disulphonic acid derivative have also been evaluated. The in vitro results agree with long-term animal data for 8 compounds but disagree in finding DAB-4'-sulphonic acid, 4-trifluoromethyl-DAB and 4-diethylaminoazo-benzene positive. Possible reasons for these divergencies are discussed. It is concluded that 9-phenylazojulolidine and N-methyl-5-phenylazoindoline have carcinogenic potential and that 3,5-dimethyl-4-aminoazobenzene and 4-aminoazobenzene-4'-sulphonic acid are likely to prove non-carcinogenic. Addition of azobenzene to the in vitro assay medium increases the transforming potency of DAB 25-fold. It is suggested that it acts as a competitive substrate for one of the enzymes that detoxify DAB, and that this effect is related to that produced by norharman. Sulphonic-acid derivatives of established carcinogens are usually inactive. The basis of this effect has been investigated, and it is suggested that it can operate by two separate mechanisms. It has been established that this assay cannot be relied upon to predict the in vivo potency of a carcinogen. Consideration has been given to possible changes which could be made to the liver activation system (the S-9 mix) currently used in in vitro carcinogenicity assays, and a diagram is presented of the metabolic conversions of a compound which might lead to mutation or tumour formation. This enables the term potential carcinogen to be accurately defined, and indicates a possible difference between absolute non-carcinogens and compounds which fail to produce cancer in vivo.
Experiments conducted in vitro are described which indicate that a family of specifically substituted phosphoramides may share the carcinogenic properties displayed by the structurally novel carcinogen, hexamethylphosphoramide (HMPA). Most of the analogues tested only gave a positive response in vitro when using a substantially modified liver homogenate activation system (S-9 mix). The analogy drawn in our earlier paper between this new class of potential carcinogens and the nitrosamine carcinogens, has been strengthened. The following compounds gave a positive response in the cell transformation assay of Styles: hexamethylphosphoramide (HMPA), hexamethylphosphorous triamide, hexamethylphosphorothioic triamide, tripiperidinophosphine oxide, phosphorothioic trimorpholide and diethoxymorpholinophosphine oxide (DEMPA).
A biologically active molecule with one or more aromatic rings often retains its activity when one of these rings is replaced by an isosteric and/or isoelectronic aromatic ring. Consideration has been given to whether this effect can be expected to apply to aromatic organic carcinogens. The literature relevant to this topic has been reviewed and the thiophene analogues of the carcinogens benzidine and 4-aminobiphenyl have been synthesized and evaluated for potential carcinogenicity. The compounds prepared were 5-p-acetamidophenyl-2-thiophenamine hydrochloride (XIII), 5-phenyl-2-thiophenamine hydrochloride (XIV), N-(5-p-acetamido-phenylthiophen-2-yl)acetamide (XV) and N-(5-phenylthiophen-2-yl)-acetamide (XVI) (see Chart for structures). Each compound was evaluated in the Salmonella reverse-mutation assay of Ames and the cell-transformation assay of Styles. The activity profiles observed for these compounds in vitro were consistent with their known chemistry, and indicate potential carcinogenicity. However, their overall chemical and biological behaviour casts doubt upon whether they would be capable of eliciting tumours in vivo. Because it is important to establish the degree of reliance which can be placed upon in vitro predictions of potential carcinogenicity generated for structurally new compounds, one of the thiophene derivatives, N-(5-phenylthiophen-2-yl)acetamide ((XVI), is currently being evaluated for carcinogenicity in mice.
Thirty-four donor corneas previously stored in McCarey-Kaufman medium containing 100 u/ml of penicillin G were transplanted into 32 recipients with a given history of penicillin allergy. There were no early or late ocular or systemic postoperative complications that could be related to a history of penicillin allergy. Thirty-two of the 34 grafts were clear on long-term follow-up, and penicillin allergy appeared to play no role in the grafts, either success or failure.
Sodium fluorescein solutions, 3 ml of 25% solution and 5 ml of 10% solution, were compared with a double-blind crossover method in a group of 41 normal volunteers and in a group of 42 patients who had diverse ophthalmic disorders. Following injection of the solutions into the antecubital vein, visualization, serial fluorescein angiograms, and five-minute phase angiograms were studied and compared. The untoward reactions reported in both studies were of types usually associated with sodium fluorescein, the most common of which was a mild, transient nausea. On the basis of our results, there is no significant difference in the incidence and severity of adverse reactions between the 10% and 25% solutions. In the volunteer study, the 25% solution was significantly superior in visualization and paired comparison (P less than .001) in the patient study, the 25% solution was significantly superior in angiogram quality (P less than .01), five-minute phase angiogram (P less than .05), and paired comparison (P less than .005). The overall superiority of the 25% concentration in a 3-ml volume was demonstrated both subjectively and objectively in the volunteer study and in the patient study.
Explore the source record for details and available documents.
Blocking the facial nerve by injecting anesthetic agent over the most posterior, most superior palpable aspect of the ramus of the mandible produces more reliably complete facial nerve akinesia than obtained by the standard techniques used to obtain facial akinesia. The position is posterior and inferior to the point chosen for the classical O'Brien block. This new technique is safe and no complications have been noted in over 10 years of use. It is highly recommended as a method of achieving total hemifacial akinesia for ophthalmic procedures.
In this paper, the author has attempted to express the prognosis for successful penetrating keratoplasty based upon a morphological classification of corneal disease. Four groups have been designated with their basic prognosis ranging from excellent to poor. The importance of appraising the diseased cornea in the area of its optimal recipient zone has been stressed. Ancillary factors adversely affecting the estimated final prognosis of keratoplasty have been considered, with emphasis upon the importance of glaucoma, lid function, tear film, ocular inflammation and patient compliance. Not only is it important for the surgeon to appraise the chance of successful surgery, but it is essential for the patient to be informed in advance regarding the probability for successful surgery and the need to comply with sometimes demanding requirements of postoperative care.
Explore the source record for details and available documents.