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A Myles

Publications and source records attributed to A Myles.

14 recordsLinked to original sources
PubMed1986

Homogeneous, liposome-based assay for total complement activity in serum.

This is a rapid, homogeneous, liposome-based assay for total complement activity in human serum. Liposome-encapsulated enzyme is unmasked by the action of complement on liposomes carrying surface-bound immune complexes. The amount of unmasked enzyme, proportional to the concentration of added complement, is quantified by measuring the absorbance of enzymically produced product at 410 nm. Complement activity in serum samples is extrapolated from a standard curve generated from dilutions of a guinea pig serum containing a known activity of complement. Interassay CVs were less than 7.0% and intra-assay CVs less than 2.8% for serum pools with complement activities spanning the normal range. Test results correlate as well with those of the hemolytic complement test (r = 0.80) as the latter correlates with itself (r = 0.82), and also correlate reasonably with measurements of complement components C3 (r = 0.62) and C4 (r = 0.74). Values for a normal population are reported. Advantages of this test include stability of reagents, speed, accuracy, simplicity, and avoidance of radioisotopes.

Alkaline Phosphatase↗
PubMed1983

Plasma prednisolone studies in rheumatic patients.

Prednisolone concentration in plasma after a daily maintenance steroid dose was monitored in 83 patients with rheumatic diseases. Although no restrictions were imposed on the intake of food or drink, plasma drug levels tended to peak at 1 h after the ingestion of the standard tablets, whereas intestinal absorption of the enteric-coated preparation was found to be most unpredictable. A profound individual variation was observed in plasma prednisolone concentrations, and neither total nor unbound drug levels showed any consistent relationship with the size of the prednisolone dose or the control of the disease activity. The basal cortisol production was suppressed in one-third of the patients. There is no support from this study for the concept of an 'optimum therapeutic range' of plasma prednisolone for the treatment of rheumatic disease.

Adult↗
PubMed1983

Histocompatibility antigens in polymyalgia rheumatica and giant cell arteritis.

Fifty-five Caucasoid patients with polymyalgia rheumatica or giant cell arteritis were typed for HLA, A, B, C and DR locus antigens. In the total patient group, DR4 had a significantly increased frequency. The prevalence of CW3 and CW6 was also significantly increased, the rise of CW3 possibly being attributable to its well-documented linkage disequilibrium with DR4. The rise in CW6 cannot be attributed to its known linkage disequilibrium with DR7.

Genes, MHC Class II↗
PubMed1977

Identification of aldophosphamide as a metabolite of cyclophosphamide in vitro and in vivo in humans.

Aldophosphamide (NSC 254), a putative key metabolite of cyclophosphamide, has now been isolated as a cyanohydrin derivative from an incubation mixture of cyclophosphamide with mouse liver microsomes in vitro and from the plasma of a cyclophosphamide-treated patient. The cyanohydrin has been shown to be identical with an authenic synthetic sample by mass spectrometry and combined gas chromatography-mass spectrometry.

Aldehydes↗
PubMed1976

Cyclophosphamide (NSC-26271)-related phosphoramide mustards- recent advances and historical perspective.

The antitumor activity of three of the most phosphoramide mustards, NSC-69947, NSC-72505, and NSC-72510, was compared with that of phosphoramide mustard (NSC-69945), the apparent active metabolite of cyclophosphamide (CP), against the L1210, P388, B16, and Lewis lung tumor systems. This comparison did not reveal any significant differences in the patterns of inhibitory activity predictive of significant advantages in the clinic of any of these compounds over CP or NSC-69945. Attempts to prepare aldophosphamide, the key intermediate in CP metabolism, by oxidation of hydroxyphosphamide under the Sarett reaction conditions lead primarily to 4-ketocyclophosphamide. Under milder conditions the product isolated appears to be the elusive aldophosphamide on the basis of positive alkylating and aldehyde tests, Rf and infrared data, and the formation and characterization of a semicarbazone. The possibility that this product is an equilibrium mixture with the tautomeric 4-hydroxycyclophosphamide has not been as yet defintely ruled out. Sarett oxidation of homohydroxyphosphamide straightforwardly gives the stable analog, homoaldophosphamide. Biologic testing of this putative aldophosphamide in direct comparison with homoaldophosphamide, CP, and NSC-69945 reveals that aldophosphamide is a potent antitumor agent indistinguishable in activity from CP and NSC-69945, whereas homoaldophosphamide is inactive. These results provide confirmatory evidence for the postulated role of aldophosphamide as an intermediate in CP metabolism and suggest, furthermore, that aldophosphamide itself is not active in vivo, requiring transformation to NSC-69945 via beta-elimination of acrolein to exert its antitumor effects. An historical account of the development of the phosphoramide mustard field is also given.

Animals↗
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Accreditation↗
PubMedDate not supplied

Iminocyclophosphamide as a chemically reactive metabolite of cyclophosphamide.

Iminocyclophosphamide has been identified among the metabolites produced by incubation of cyclophosphamide with cytochrome P-450 mono-oxygenase immobilized on beaded Sepharose. The reactive imine was trapped by addition of hydrogen cyanide, and the product, 4-cyanocyclophosphamide, was identified by comparison of its chromatographic and mass-spectral properties with those of a synthetic standard. Iminocyclophosphamide was also generated chemically from 4-hydroperoxycyclophosphamide and characterized both by addition of hydrogen cyanide and by reduction with sodium borodeuteride. The synthesis of authentic 4-cyanocyclophosphamide is also reported.

Animals↗