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Biomedical subjects

M D Green

Publications and source records attributed to M D Green.

At least 109 records · Page 6Linked to original sources
PubMed1992

In vitro evidence for direct complexation of ADR-529/ICRF-187 [(+)-1,2-bis-(3,5-dioxo-piperazin-1-yl)propane] onto an existing ferric-anthracycline complex.

ADR-529 protects against anthracycline cardiotoxicity, possibly by preventing free radical induction. We hypothesize that this occurs by ADR-529 forming a ternary anthracycline-iron-ADR-529 complex. This study used 200-MHz Fourier-transformed NMR to demonstrate the ability of ADR-529 to do this. Peak assignments were by proton-correlated spectroscopy and proton-carbon heteronuclear-correlated spectroscopy. Ga3+ served as a probe for Fe3+, and D2O was the system solvent. Doxorubicin and epirubicin were the studied drugs. Proton spectra of multiple combinations (including pure standards as controls) were obtained. Both Ga3+ plus ADR-529 and Ga3+ plus doxorubicin showed evidence of complexation, as seen by appropriate peak shifts and changes in the associated coupling constants. Ga3+ plus ADR-529 plus epirubicin showed complexation different from that of Ga3+ plus ADR-529 or Ga3+ plus doxorubicin and consistent with the proposed structure. We conclude that ADR-529 would be able to form a ternary complex with an existing anthracycline-Fe3+ complex in an isolated aqueous environment.

Antibiotics, Antineoplastic↗
PubMed1991

Biomedical applications of high-performance liquid chromatography-mass spectrometry with continuous-flow fast atom bombardment.

This report describes the application of high-performance liquid chromatography combined with continuous-flow fast atom bombardment mass spectrometry to analytical problems in the biomedical laboratory. Applications include the compound-specific detection of diagnostic acylcarnitines in human urine, the separation and analysis of acyl-coenzyme A thioesters, and qualitative studies on complex mixtures of modified peptides (dansyl and dinitrophenyl derivatives). For each of these applications standard analytical columns (3.9 mm I.D.) and 1 ml/min flow-rates were employed with post-column stream splitting (1:100) before mass spectrometry. Various mobile phase compositions and solvent gradients were employed. The addition of 1-5% glycerol to the mobile phase was shown to have little effect on the chromatography. For all compounds studied (acylcarnitines, acyl-coenzyme A thioesters, and derivatized peptides) molecular weight information was obtained and sufficient sensitivity was achieved to allow unambiguous identification of trace components in complex mixtures.

Acyl Coenzyme A↗
PubMed1991

Reversal of a neurologic paraneoplastic syndrome with octreotide (Sandostatin) in a patient with glucagonoma.

A 69-year-old woman with classic glucagonoma syndrome had associated progressive neurologic disease manifest as dementia, ataxia, optic atrophy, and lower limb weakness. Visual evoked responses (VERs) were absent bilaterally. After an attempt at resection was unsuccessful, therapy was started with somatostatin analogue (Sandostatin, SMS 201-995). Over the ensuing 3 months, there was a decrease in the plasma glucagon level, resolution of the rash, weight gain, reversal of the dementia, and an improvement in coordination and limb weakness. Subsequent VERs revealed bilateral delayed responses.

Aged↗
PubMed1991

New anthracycline antitumor antibiotics.

Doxorubicin is an essential component of the treatment of aggressive lymphoma, childhood solid tumors, bone and soft tissue sarcomas, and breast cancer and additional indications are emerging. On the other hand, daunorubicin has occupied the central position of interest in the treatment of acute leukemia. Epirubicin has a spectrum very similar to doxorubicin but lesser toxicity. The ability to protect against cardiotoxicity with ICRF-187 further enhances clinical interest in exploiting modifications in doze intensity to therapeutic advantage. Idarubicin has at least equivalent activity to daunorubicin and doxorubicin in leukemia. New areas of research in relation to anthracycline antibiotics include introduction of new the analogs, insight into mechanisms of resistance, the reversal of multidrug resistance in vitro, the protection of cardiac toxicity, and the study of other important biochemical reactions relevant to cytotoxicity. Orally active anthracyclines such as idarubicin and compounds which lack cross-resistance with the parent drugs or have other mechanisms for cytotoxicity are being developed. It is likely that these modifications will lead to an expanding therapeutic spectrum for these already widely useful drugs.

Aclarubicin↗
PubMed1991

Recent advances in carcinoids and gastrointestinal neuroendocrine tumors.

The main advances in the management of carcinoid and gastrointestinal neuroendocrine tumors have been in the areas of imaging and therapy. New techniques have been developed to detect and identify the sites of tumor so that correct therapeutic decisions can be made. Although surgery remains the mainstay of treatment of localized and some cases of advanced disease, the use of biologic agents and new drugs has proven valuable in those patients in whom surgery is not indicated. These include interferon-alpha, the somatostatin analogue octreotide, omeprazole. Different methods of delivery have been investigated with mixed success. Future progress in the understanding and management of neuroendocrine tumors is likely to be slow due to their rarity and long natural history.

Carcinoid Tumor↗
PubMed1991

Extracorporeal photochemotherapy in the treatment of cutaneous T-cell lymphoma. Complexity of objective evaluation.

The term cutaneous T-cell lymphoma (CTCL) encompasses the spectrum of diseases characterized by a monoclonal proliferation of malignant T lymphocytes predominantly of the mature T-helper cell type. These include mycosis fungoides, which is usually localized to the skin for many years, and the Sezary syndrome, the leukemic variant in which characteristic, bizarre lymphatic cells with deeply indented or cerebriform nuclei, the Sezary cells, infiltrate lymph glands and internal organs such as the spleen, liver, lungs, heart, and bone marrow. The condition is more common in men after their fourth decade. The treatment of CTCL varies depending on the stage of the disease. The skin of the patient is the primary index of effectiveness of therapy. Options range from topical steroids, topical nitrogen mustard, X-irradiation, electron beam irradiation, and 8-methoxypsoralen (8-MOP) combined with ultraviolet A photochemotherapy (PUVA), to leukapheresis and systemic chemotherapy. More recently, extracorporeal photochemotherapy (ECPC) has been introduced. The safety and efficacy of this modality is further investigated in six patients who fulfilled the criteria of diagnosis of CTCL. The problems encountered in objectively evaluating the clinical responses in the patients are outlined and improvements in the protocol to overcome these are suggested. The proposed mechanism of action is an immunostimulatory one and a procedure that is relatively free from side effects; it offers promise as a potential treatment for a difficult cancer.

Aged↗
PubMed1991

Recombinant alpha-2b interferon in patients with malignant carcinoid tumour.

Seventeen patients with malignant carcinoid tumour, ten of whom had the malignant carcinoid syndrome, were treated with recombinant alpha-2b interferon by subcutaneous injection (3 MU per dose) three times per week for a median of 12 weeks (range 4-48). No objective tumour responses were observed; however, there was a greater than 50% reduction in 24-hour urinary 5-hydroxyindolacetic acid (5-HIAA) excretion in four of ten patients (40%) with elevated pretreatment levels. Five of ten patients (50%) with flushing, five of seven patients (71%) with diarrhoea and both patients with wheezing experienced relief of symptoms. Three of four patients (75%) with weight loss as their only problem experienced weight gain. Responses occurred within the first eight weeks of treatment, but were generally of short duration. Toxicity occurred in all patients, and consisted mainly of fever, chills, anorexia, fatigue and weight loss. Four patients ceased therapy due to toxic reactions. Although interferon has activity against carcinoid tumours, its benefits are short-lived and toxicity limits its use with increasing dose. Patients with carcinoid syndrome appear to achieve the best therapeutic response, and it is likely that low doses (9-20 million IU weekly) are as effective as higher doses (36-72 million IU weekly).

Adult↗
PubMed1990

Characterization and primary sequence of a human hepatic microsomal estriol UDPglucuronosyltransferase.

A human liver microsomal UDP glucuronosyltransferase (UDPGT) that demonstrates reactivity with estriol (pI 7.4 UDPGT) has been purified to homogeneity and characterized further. No activity toward morphine, 4-hydroxybiphenyl, bilirubin, or tripelennamine was observed. The estriol UDPGT shows immunoreactivity with antibodies raised against rat hepatic microsomal 3 alpha- and 17 beta-hydroxysteroid UDPGTs but not with antibodies raised against rat hepatic microsomal p-nitrophenol UDPGT. The NH2-terminal sequence of the purified protein was determined and found to correspond to an identical sequence in the deduced amino acid sequence of a cDNA obtained from a human liver library in lambda gt11 (HLUG4). Sequence analysis revealed that HLUG4 is 2094 bp in length and encodes a protein of 523 amino acids which has a 16 amino acid leader sequence, followed by an untranslated 3' region of 525 bp. Three potential N-glycosylation sites were identified in the predicted sequence. The deduced amino acid sequence of estriol UDPGT showed 82% identity with the deduced amino acid sequence of another human hepatic cDNA (HLUG25), which has been expressed as a UDPGT capable of 6 alpha-hydroxyglucuronidation of hyodeoxycholic acid, strongly suggesting that these proteins are members of the same gene subfamily.

Amino Acid Sequence↗
PubMed1990

Role of (+-)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane (ICRF-187) in modulating free radical scavenging enzymes in doxorubicin-induced cardiomyopathy.

This study was designed to investigate the mechanism by which (+-)-1,2-bis(3,5-dioxopiperazinyl-1-yl)propane (ICRF-187) protects against doxorubicin cardiotoxicity. Others have hypothesized that the major factor contributing to doxorubicin cardiotoxicity is the depletion of the antioxidant defense mechanisms of the heart induced by doxorubicin. Mice were acutely (24-h exposure) or chronically (13-week exposure) treated with doxorubicin to develop a model for cardiotoxicity. Five-week-old BALB/c mice were given i.p. injections of doxorubicin alone or 30 min after ICRF-187, while control mice received ICRF-187 or 0.9% NaCl solution alone without doxorubicin. Electron microscopy of the mouse hearts demonstrated conclusively that doxorubicin was cardiotoxic after 13 weeks of exposure, showing mitochondrial degeneration and disruption of the myofibrillar organization. Furthermore, normal morphology of the electron micrographs after treatment with doxorubicin and ICRF-187 indicated that ICRF-187 was cardioprotective. The activities of the antioxidants superoxide dismutase, glutathione peroxidase, and catalase and the concentration of reduced glutathione were measured in the heart, liver, kidneys, and skeletal muscle of mice treated with doxorubicin, ICRF-187, or the drug combination. After acute or chronic exposure to the drugs there was no significant difference in enzyme or reduced glutathione levels compared to the control mice in any of the treatment groups. It was concluded that neither the cardioprotective effect of ICRF-187 nor the cardiotoxicity induced by doxorubicin was related to an effect on cardiac antioxidants, but rather another mechanism operated in this particular model.

Animals↗
PubMed1990

Pharmacokinetics and toxicity of two schedules of high dose epirubicin.

Epirubicin, a stereoisomer of doxorubicin, is reported to have equal antitumor activity with lower cardiac and systemic toxicity. Recently the maximum tolerated dose of this drug has been revised upwards with reported increased response rates. However, the pharmacokinetics of epirubicin at high doses have never been reported. Accordingly, this study was designed to evaluate the pharmacokinetics of epirubicin when administered as either a 15-min i.v. bolus or a 6-h i.v. infusion in a phase I study at high doses. Nineteen patients with a variety of malignancies were given a total of 52 cycles of epirubicin at doses of 90 to 150 mg/m2 given once every 3 weeks. The maximum tolerated dose was 150 mg/m2 epirubicin given either as a bolus or as an infusion. The major dose-limiting toxicity was neutropenia. Interpatient variation occurred in the pharmacokinetics at each dose level but overall there were dose-dependent pharmacokinetics. This was manifested as a disproportionate increase in plasma levels and areas under the curve as the epirubicin dose was increased from 90 to 150 mg/m2. The pharmacokinetics of epirubicin could best be described by an open two-compartment model. Peak plasma concentrations were attained at a median of 12 min following the bolus injection and concentrations approached the steady state within a median of 55 min following the start of the 6-h infusion. Administration of the 150 mg/m2 dose over the 6 h compared to the bolus administration was associated with a 92% decrease in peak concentration from 3088 +/- 1503 to 234 +/- 126 ng/ml. This was not associated with an appreciable change in hematological or nonhematological toxicities. The median distribution half-life was 10 min and the median elimination half-life was 42.0 h. The cumulative renal excretion of the parent compound accounted for less than 2% of the administered dose. The major metabolites in both plasma and urine samples were 4'-O-beta-D-glucuronyl-4'-epidoxorubicin, 13-S-dihydro-4'-epidoxorubicin, and 4'-O-beta-D-glucuronyl-13-S-dihydro-4'-epidoxorubicin. This study demonstrates that a 135 mg/m2 bolus infusion given on a 3-weekly schedule is an appropriate initial dose for further clinical studies.

Biotransformation↗
PubMed1990

Phase II study of esorubicin (4'deoxydoxorubicin) in anthracycline naive patients with ovarian cancer.

Sixteen patients with metastatic ovarian cancer who had not previously been treated with anthracyclines were treated with 4'deoxydoxorubicin at a dose of 30 mg/m2 intravenously every 3 weeks. There were no clinical responses in this group of patients. Toxicities were infrequent with neutropenia and thrombocytopenia being dose limiting. Nausea and vomiting occurred in only 4 patients. We conclude that 4'deoxydoxorubicin is an inactive drug in this patient population and does not warrant further investigation in this disease.

Adult↗
PubMed1990

Inhibition of human periodontal prostaglandin E2 synthesis with selected agents.

Considerable evidence has demonstrated the importance of PGE2 synthesis in the pathogenesis of periodontal disease. Although various cyclooxygenase inhibitors have been known to block periodontal PGE2 synthesis and prevent disease progression in animal models, there are few reports comparing relative efficacies of various inhibitors of arachidonic acid (ARA) metabolism. We have developed a sensitive in vitro assay to measure PGE2 synthesis in periodontal tissues. The apparent IC50 values (i.e. the concentration of drug which causes 50% inhibition of maximum PGE2 synthesis) have been determined for a series of arachidonic acid analogues as well as competitive and non-competitive cyclooxygenase inhibitors. Periodontal tissue homogenates were incubated in the presence of 3H-arachidonic acid for 45 min at 37 degrees C. Inhibitors were tested at 10(-10)-10(-4) M and at zero concentration to measure conversion of 3H-arachidonate to 3H-PGE2. Log or half log dilutions of inhibitors were tested in triplicate for each assay. Radiolabeled PGE2 was extracted from homogenates, purified by reverse phase chromatography and quantitated by double antibody capture. RIA was performed on each homogenate to determine the amount of endogenous unlabeled PGE2 present in the sample to correct for antibody capture recovery. The apparent IC50 values were determined for each drug by averaging two or more replicate assays. Specific total enzymatic activity of periodontal tissue homogenates was typically 5-11 pg PGE2/min/mg tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Arachidonic Acid↗
PubMed1990

Evidence of the selective alteration of anthracycline activity due to modulation by ICRF-187 (ADR-529).

Anthracyclines are powerful anticancer drugs whose use is limited by the development of chronic cardiotoxicity. The bisdioxopiperazine compound ICRF-187 (ADR-529) specifically abrogates this toxicity both in preclinical animal models and in humans. It does this without effecting either the acute toxicities or the anticancer activity. Therefore, with a specific antagonist, the mechanism of activity of the anthracyclines can be explored. This review discusses recent clinical trials and animal models addressing this issue and concludes by hypothesizing a mechanism of action.

Animals↗