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Biomedical subjects

D W Miles

Publications and source records attributed to D W Miles.

16 recordsLinked to original sources
PubMed1992

Induction of soluble tumour necrosis factor receptors during treatment with interleukin-2.

Interleukin-2 (IL-2) treatment induces other cytokines such as tumour necrosis factor (TNF) TNF may mediate some of the anti-tumour activity of IL-2, but conversely, may contribute to its dose limiting toxicities. Cleaved extracellular domains of the p55 and the p75 TNF receptors (sTNF-R1 and R2) bind to and inhibit the biological activity of TNF in vitro, but may also act as carrier molecules. We have assayed TNF and sTNFR-1 and 2 in the plasma of advanced cancer patients, before and during treatment with IL-2. Plasma levels of TNF in 22 patients were not significantly different from 25 normal controls, but levels of sTNFR-1 and sTNFR-2 were higher (P < 0.001). Levels of TNF and both its soluble receptors were significantly increased in 13 patients receiving IL-2 therapy. Maximum induced levels of sTNFR-1 and sTNFR-2 correlated closely with maximum induced levels of TNF (P < 0.001), but peak levels of sTNFR-1 and two were achieved 24-48 h after peak TNF. Levels of TNF and sTNF-Rs did not correlate with toxicity. Treatment with IL-2 leads not only to induction of TNF but also soluble binding proteins at levels which may modulate its biological activity.

Breast Neoplasms↗
PubMed1991

Activity and toxicity of carboplatin and iproplatin in relapsed high-grade glioma.

A total of 15 patients with relapsed high-grade glioma were treated with carboplatin (400 mg/m2) or iproplatin (300 mg/m2). All had received previous radiotherapy, and 12 had previously undergone chemotherapy. One of the ten patients treated with carboplatin and one of the five treated with iproplatin achieved a partial remission as determined by repeat computerised tomographic (CT) scan. Myelosuppression was considerable, as three patients developed grade IV neurotoxicity, which was fatal in one case. Although carboplatin and iproplatin showed activity against malignant glioma, the study was closed because of unacceptable toxicity.

Adult↗
PubMed1991

High-dose epirubicin as primary chemotherapy in advanced breast carcinoma: a phase II study.

A total of 40 patients with metastatic breast cancer were treated with 120 mg/m2 i.v. epirubicin every 3 weeks for a maximum of 10 cycles. Nine achieved a complete response and 17 showed a partial response, for an objective response rate of 65% (95% confidence interval, 47%-83%); the median duration of response was 7 months (range, 1-15 months) and median survival amounted to 13 months (range, 2-20 months). Leucopenia (grade 2 or 3) was seen in 14 patients on day 21 of the cycle. A subset of nine patients underwent blood counts on day 10, when all had marked neutropenia (less than 1 x 10(9)/l). Other toxicity was frequent and included nausea/vomiting (80%), alopecia (95%) and stomatitis (35%). Five patients showed a significant fall in cardiac output, but this reverted to normal after treatment. Epirubicin should have a role in the development of high-dose regimens for the treatment of advanced breast cancer.

Adult↗
PubMed1991

Intensive weekly chemotherapy for good-prognosis patients with small-cell lung cancer.

A weekly, intensive chemotherapy regimen has been used to treat 70 patients with small-cell lung cancer (SCLC). Forty-five patients had limited disease (LD) and 25 extensive disease (ED) with good prognostic features. The regimen consisted of cisplatin 50 mg/m2 intravenously (IV) day 1 and etoposide 75 mg/m2 IV days 1 and 2, alternating weekly with ifosfamide 2 g/m2 IV day 8 and doxorubicin 25 mg/m2 IV day 8, for a total of 12 weeks. Dose modifications were made according to defined hematologic criteria. Responding patients with limited disease subsequently received mediastinal radiotherapy. Overall response to chemotherapy was 91% with a complete response (CR) rate of 50%. Forty-five patients with limited disease (LD) achieved an overall response rate of 91% with a CR rate of 51%, and 25 patients with extensive disease (ED) achieved an overall response rate of 92% with a CR rate of 48%. Median survival for the whole group was 54 weeks (LD, 58 weeks; ED, 42 weeks). Hematologic toxicity was predictable, without the wide fluctuations in WBC count seen in conventional 3-weekly regimens. In all, one quarter of treatment courses were delayed, most frequently because of leukopenia. Dose reductions were required in 63% of cases. The average delivered dose intensity was calculated and shown to be 73% of projected. Nonhematologic toxicity was mild with nausea and vomiting being the most common. This weekly schedule of chemotherapy has proved to be active and well tolerated and is currently being compared with conventional 3-weekly chemotherapy in a randomized study.

Adult↗
PubMed1990

Mitomycin, ifosfamide and cisplatin in non-small-cell lung cancer.

Chemotherapy with mitomycin C, ifosfamide and cisplatin (MIC) is reported to produce responses of 56% and 69% in inoperable non-small-cell lung cancer (NSCLC). We evaluated the regimen in 45 similar patients who received up to six courses of 6 mg/m2 mitomycin C, 3 g/m2 ifosfamide, and 50 mg/m2 cisplatin every 3 weeks. In all, 18 patients had limited disease (LD) and 27 had extensive disease (ED). A total of 18 patients responded (40%), 9/18 with LD and 9/27 with ED; there were 4 complete responders. The median duration of response was 25 weeks, and median survival was 32 weeks (range, 2-96 weeks). Toxicity was moderate. Nausea and vomiting were controlled with i.v. dexamethasone and high-dose metoclopramide. Other toxicities included myelosuppression and alopecia. This study confirms that MIC is one of the most active regimens for treatment of NSCLC, with acceptable toxicity.

Adult↗
PubMed1989

Intensive chemotherapy with autologous bone marrow transplantation for small-cell lung cancer.

Since 1980, 75 patients with small-cell lung cancer (SCLC) have been entered into four consecutive studies of high-dose chemotherapy using autologous bone marrow transplantation (ABMT) to assist haematological recovery. In the first study, 25 patients were treated with cyclophosphamide (160-200 mg/kg) as the sole chemotherapy; in the second (26 patients), the cycle of high-dose cyclophosphamide (with or without 800-1,200 mg/m2 etoposide) was repeated as induction treatment. In the first study, response was high [14 complete responses (CR), 7 partial responses (PR)] but was not increased by repeating the cycle (15 CR, 8 PR), and survival was slightly worse in the second trial. In the third study, 15 patients were treated with doxorubicin, vincristine and etoposide for two cycles and then with 200 mg/kg cyclophosphamide. Although high-dose cyclophosphamide increased the complete response rate, the additional responses were short-lived. In the final study, an attempt was made to increase the initial CR rate by combination chemotherapy using carboplatin (400-600 mg/m2), etoposide (120 mg/m2 x 4) and either high-dose cyclophosphamide (40 mg/kg x 4) or melphalan (140 mg/m2). Although all nine patients responded, none underwent a CR. The long-term survival (up to 7 years) does not appear to be different from that in comparably selected cases treated with conventional chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1979

Conformation of nucleosides: circular dichroism study on the syn-anti conformational equilibrium of 2-substituted benzimidazole nucleosides.

The solution conformations of 2-substituted derivatives of 1-(beta-D-ribofuranosyl)benzimidazole have been determined by circular dichroism spectroscopy in aqueous solutions. It is shown that analogs with methyl, amino, or methylamino substituents at position 2 of the benzimidazole ring (position 8 of the purine ring) have predominantly anti conformations, whereas analogs with chloro, aza, methoxy, or methylmercapto substituents have predominantly syn conformations. The preferred solution conformations of the benzimidazole nucleosides and analogous purine nucleosides are compared. The results demonstrate that the replacement of nitrogen by carbon at position 3 of the purine ring of purine (beta) nucleosides leads to important conformational consequences, which are strengthened or neutralized by substituents at position 8 of the purine ring.

Benzimidazoles↗
PubMed1979

Interferon induction: a conformational hypothesis.

The ability of polynucleotides or polynucleotide duplexes such as poly(I).poly(C) to induce interferon production is proposed to depend on the existence of certain stable glycosidic orientations. It appears that a slight increase in instability of 1--3 kcal/mole (1 cal = 4.184 J) in the conformational regions near 20 degrees, 80 degrees, and 160 degrees leads to a loss of potency with respect to interferon induction. Thus, it is proposed that, for a polynucleotide to exist in the overall conformation necessary for interferon induction, stability of glycosidic orientations near 20 degrees, 80 degrees, and 160 degrees may be necessary to confer flexibility and activity on polynucleotide structures. This proposed conformational triad of stable conformational regions essential to interferon induction is based on the results of conformational energy calculations of the glycoside rotational profiles of adenosine, 7-deazaadenosine, inosine, and 7-deazainosine, as well as the conformational properties of other purine nucleoside analogs, and on inferences derived from calculations about the conformational effect in polynucleotides of removing the 2'-OH group.

Adenosine↗
PubMed1978

A conformational basis for the antiviral inactivity of tetrazole ribonucleosides.

The antiviral activity of ribavirin has been associated with its inhibition of the enzyme, IMP dehydrogenase. The ability of ribavirin to inhibit this enzyme has previously been shown to be related to its stability in the high anti glycosidic conformation. The antiviral effectiveness of several analogs of ribavirin have been investigated recently. The evidence indicates their antiviral effectiveness is related to their stability in the high anti conformation. Recently the disposition of purine analogs that pass through the inosine monophosphate branch point has been investigated. The results of these studies are consistent with the concept that the conversion of IMP to XMP requires the high anti conformation and that the conversion of IMP to adenylosuccinate requires some other conformation, possibly the anti conformation.

Azoles↗
PubMed1977

Circular dichroism of adenosine dinucleotides.

The circular dichroism and absorption spectra of (3'-5')ApA, (5'-5')AppA, and (5'-5')ApcpA [diadenosine(5'5') pyrophosphonate] under various ionic coditions and at various temperatures are reported. Temperature studies reveal that under the same ionic strength and solvation conditions the probability of base-base interaction is ApA greater than AppA greater than ApcpA. It is found that increasing the molar refractivity of the solvent decreases the base-base interaction for both ApA and AppA and that both compounds proceed to a monomeric state in solvents of high molar refractivity. Solvent effect studies also indicate that a major percentage of the driving force for the base-base interaction can be accounted for by London dispersion forces. Low ionic strength appears to favor the base-base interacted conformation. All compounds tend toward the same noninteracted form at high temperatures. Plots of [theta]lambda against X (where X is an experimental parameter) were constructed in order to obtain information concerning which transitions might be undergoing oscillator coupling. To a first approximation, transitions coupled to each other should have very similar deta[theta]lambda/detaX for the experimental range of X. Applying this technique to the experimental data yielded information concerning possible transition coupling.

Adenine Nucleotides↗
PubMed1977

Conformational basis for the activation of adenylate cyclase by adenosine.

The ability of adenosine to stimulate adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] and increase adenosine 3':5'-cyclic monophosphate (cAMP) levels has important biochemical consequences. These include the suppression of immune responses and cardiovascular effects. Recent investigations involving the ability of adenosine and adenosine analogs to stimulate adenylate cyclase provided experimental data that appear to be correlated with the ability of adenosine and analogs of adenosine to exist in the glycosidic high anti conformation. 9-beta-D-Arabinofuranosyladenine, which is not stable in the high anti conformation, is inactive as a stimulator of adenylate cyclase. 2'-Deoxyadenosine is also not stable in the high anti conformation but its instability may be significantly decreased by intramolecular adjustments promoted by receptor or active site interactions. 2'-Deoxyadenosine does not activate adenylate cyclase in lymphocytes when ATP is the substrate but is able to activate adenylate cyclase when 2-fluoro ATP is the substrate. The inability of certain analogs of adenosine, with bulky groups substituted for hydrogen at the 8 position of the adenine base, to activate adenylate cyclase and increase either lymphocyte or cardiac cell cAMP levels is consistent with the designation of the high anti conformation as being the conformation required for the activation of adenylate cyclase. An understanding of the glycosidic conformation required by the extracellular adenosine receptor of the adenosine molecule provides the basis for designing nucleoside analogs of adenosine that will exert a desired effect on cAMP levels. The avoidance of unwanted immunosuppressive or cardiotoxic effects can be arranged by structural changes that prohibit the high anti conformation.

Adenosine↗
PubMed1976

Theoretical studies of the conformational properties of ribavirin.

One of the factors required for the antiviral activity of the synthetic nucleoside, ribavirin (1-beta-D-ribofuranosyl-1,2,4-triazole-3-carboxamide), is the ability of the molecule to adopt the substrate conformation specified by the enzyme for which it is a competitive inhibitor, inosine 5'-phosphate dehydrogenase (IMP:NAD+ oxidoreductase, EC 1.2.1.14). The calculated glycosidic minimum for ribavirin is the high syn conformation, which is in agreement with experimental determinations of the molecule's solution conformation. The similarity in solution between the conformation of the active ribavirin molecule and the conformation of its inactive 5-methyl and 5-chloro derivatives indicate that some other substrate conformation is specified by the enzyme. The high anti conformation, found by these calculations to be close in energy to the high syn minimum, is postulated to be the active conformation required by the enzyme. The inactivity of the 5-methyl and 5-chloro derivatives is attributed to the much greater stability of these derivatives in the inactive high syn conformation.

Binding Sites↗
PubMed1976

Comparative study by circular dichroism of the conformation of deazapurine nucleosides and that of common purine nucleosides.

Purine nucleoside analogs modified by replacement of the nitrogen atom at the 3 position by a CH group give a characteristic circular dichroism curve that is not substantially modified by chemical substitution at the 8 position. Since it is rather well established that 8-substituted purine nucleosides are predominantly in the syn conformation in aqueous solution, it follows that the 3-deazapurine nucleosides, whether substituted at position 8 or not, also favor the syn conformation. These data are in sharp contrast to the circular dichroism data obtained on 8-halogenated and 8-alkylated derivatives of adenosine and guanosine, which give circular dichroism profiles substantially different from those obtained on the parent compounds. Certain purine-nucleoside-utilizing enzymes fail to interact effectively with either the unsubstituted 3-deaza analogs or the 8-substituted derivatives of adenosine and guanosine. The hypothesis recently given that the inactivity of the 8-substituted derivatives springs from their syn-conformational preference is tentatively accepted to explain the inactivity of the 3-deaza analogs.

Adenosine↗