Search PubMed⌕ Search

Biomedical subjects

A M Jordan

Publications and source records attributed to A M Jordan.

At least 19 recordsLinked to original sources
PubMed2001

Melanocyte-Directed enzyme prodrug therapy (MDEPT): development of second generation prodrugs for targeted treatment of malignant melanoma.

Evaluation of second generation prodrugs for MDEPT, by oximetry, has highlighted structural properties that are advantageous and disadvantageous for efficient oxidation using mushroom tyrosinase. In particular, a sterically undemanding prodrug bis-(2-chloroethyl)amino-4-hydroxyphenylaminomethanone 28 was synthesised and found to be oxidised by mushroom tyrosinase at a superior rate to tyrosine methyl ester, the carboxylic acid of which is the natural substrate for tyrosinase. The more sterically demanding phenyl mustard prodrugs 9 and 10 were oxidised by mushroom tyrosinase at a similar rate to tyrosine methyl ester. In contrast, tyramine chain elongation via heteroatom insertion was detrimental and the rate of mushroom tyrosinase oxidation of phenyl mustard prodrugs 21 and 22 decreased by 10 nanomol/min.

Agaricales↗
PubMed1999

Melanocyte-directed enzyme prodrug therapy (MDEPT): development of a targeted treatment for malignant melanoma.

A novel prodrug rationally designed to function as a tyrosinase substrate has been synthesised to allow targeted treatment of malignant melanoma. This agent has been evaluated for tyrosinase-mediated drug release, and has been shown to act in the desired manner. Furthermore, differential cytotoxicity has been demonstrated in cell lines which express tyrosinase and those which do not.

Animals↗
PubMed1995

Control of tsetse flies (Diptera: Glossinidae) with the aid of attractants.

A high degree of control of some Glossina spp. can be achieved by trapping. This is mainly because of their adenotrophic vivaparity, and consequently very low intrinsic rates of population increase. Calculations based on basic life table data have shown that it is only necessary to catch some 1-4% of the female population per day in order to achieve effective control. This is at least 8 times less than that required for Anopheles albimanus. Much attention has been given to the size and shape of traps. In general for the Palpalis Group of species, the vertically oriented biconical trap and its derivatives are highly effective, whereas for the Morsitans Group compact or horizontally oriented shapes are more attractive. Royal blue is highly attractive, and strongest landing responses are induced either on dark surfaces or those strongly reflective in the ultraviolet. Only carbon dioxide has been identified as an attractant for the Palpalis Group, but its use in traps is impractical. In contrast, a number of attractive compounds have been identified for the Morsitans Group, but there is much variation between species and within a species at various locations. A cocktail of all known attractants, except carbon dioxide, can increase trap captures of Glossina pallidipes by 15-20 times. Attractive substances in host breath include acetone, and in urine, 4-methyl phenol and 3-n-propyl phenol. The new generation of traps, or so-called targets, usually insecticide-impregnated that do not retain attracted flies, can be highly effective for controlling tsetse populations.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

The Tsetse Research Laboratory.

The Tsetse Research Laboratory in Bristol was opened in December 1962, with the initial objective of developing techniques for rearing tsetse flies on a large scale outside Africa. Its work has, however, extended greatly since then. This article highlights the research undertaken at the Laboratory, not only on the breeding of tsetse flies but also on various aspects of their biology and control.

Animals↗
PubMed1989

Rationale for intravesical chemotherapy in the treatment and prophylaxis of superficial transitional cell carcinoma.

1. A thorough evaluation of the urinary tract is an integral part of the initial management of a patient with transitional cell carcinoma. The site of all urothelial abnormalities must be determined and adequate histologic material obtained and reviewed. The urothelium not involved by obvious tumor should also be evaluated by either cytology or mucosal biopsies. All patients with high grade tumor should have a biopsy from the prostatic urethra. 2. The clinician should determine the risk of progression by evaluating the tumor grade, stage, and the presence or absence of carcinoma in situ. 3. The likelihood of a recurrence following endoscopic resection of a superficial bladder tumor ranges from 20% for a solitary low grade tumor to over 90% for a patient with multifocal high grade cancer. 4. The reasons for the high incidence of a subsequent tumor include new occurrences related to the continued contact of carcinogens with the susceptible urothelium, failure to completely resect all tumor, and possibly the implantation of tumor cells on the altered urothelial surface following endoscopic resection. 5. Intravesical instillation of antineoplastic agents is capable of reducing the incidence of a subsequent tumor when used for prophylaxis. These agents are also capable of eradicating residual tumor. 6. The clinician should determine whether intravesical therapy is being used for treatment or prophylaxis. 7. Thiotepa is a relatively inexpensive and safe intravesical chemotherapeutic agent which, when used for treatment of existing tumor, will provide a complete response rate of from 35 to 45%. There is a suggestion that it is more effective in low grade than high grade tumors. Prospective randomized trials indicate that patients receiving Thiotepa are less likely to develop a subsequent tumor in a given period of time than patients who do not receive intravesical therapy. 8. Mitomycin-C will provide a complete response rate in high risk patients from 35 to 50% when used for treatment of existing tumor. Approximately 15% of such patients will progress to muscle invasion if followed for approximately three years. There are few randomized trials using Mitomycin-C to determine its efficacy for prophylaxis. 9. BCG has been used for treatment and prophylaxis of superficial bladder cancer. It is relatively inexpensive. The side effects vary with the strain. Several strains have been used but they have not been compared in randomized trials. When used for treatment, the complete response rate ranges from 50 to 65%.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Intravesical↗
PubMed1987

Transitional cell neoplasms of the urinary bladder. Can biologic potential be predicted from histologic grading?

The concept that most transitional cell neoplasms of the urinary bladder exist as either nonaggressive lesions of low cytologic grade or aggressive anaplastic cancers is gradually gaining acceptance. The extent to which the biological potential of these neoplasms is revealed in their pathologic features is the subject of this article. Using guidelines developed in experimental models, a series of 400 transitional cell neoplasms selected for long-term follow-up were classified into the WHO system. The results indicate that (1) almost all transitional cell tumors can be grouped into low and high grades at initial presentation; (2) the low grade lesions (usually designated transitional cell carcinoma, Grade I) are benign and should be called papillomas rather than carcinomas; (3) the risk of progression is not a function of the number of recurrences for these noninvasive, low-grade, papillary tumors; (4) the high-grade neoplasms are aggressive whether papillary or nodular and account for greater than 93% of tumor-related deaths; (5) patients with high-grade lesions have a reduced life expectancy even if progression does not occur; (6) depth of invasion and growth pattern are limited as predictive factors compared with histologic grade; (7) histologic grading of the initial tumor tissue can be highly predictive of outcome.

Adult↗
PubMed1978

Principles of the eradication or control of tsetse flies.

The success of attempts to control African trypanosomiasis afflicting both men and animals through the destruction of the tsetse vector depends on a realistic assessment of human and ecological factors in infested regions. The complete eradication of tsetse is at present possible only in limited areas, and elsewhere the advantages of periodic control campaigns have to be weighed carefully against their cost.

Agriculture↗