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Biomedical subjects

M Brune

Publications and source records attributed to M Brune.

At least 73 records · Page 4Linked to original sources
PubMed1996

Remission maintenance therapy with histamine and interleukin-2 in acute myelogenous leukaemia.

Peripheral blasts recovered from patients with acute myelogenous leukaemia (AML) were efficiently lysed by interleukin-2 (IL-2)-activated heterologous natural killer (NK) cells in vitro. The IL-2-induced killing of AML blasts was inhibited by monocytes, recovered from peripheral blood by centrifugal elutriation. Histamine, of concentrations within the micromolar range, abrogated the monocyte-induced inhibition of NK-cells; thereby, histamine and IL-2 synergistically induced NK-cell-mediated killing of AML blasts. The effect of histamine was apparently mediated by H2-type histamine receptors (H2R), since the H2R antagonist ranitidine completely blocked the response. Based on these in vitro findings, seven patients with AML in first (n=2), second (n=3) or third (n=2) complete remission (CR) were given home therapy with interleukin-2 (IL-2; O.9 x 10(6) IU x 2 s.c.) and histamine (0.4 - 0.7 mg x 2 s.c.) in cycles of 21 d, separated by 6-week intervals. The patients also received treatment with low dose cytarabine and thioguanine between cycles of histamine/IL-2. Toxicity was moderate and include local reactions to IL-2 at the site of injection and short-lasting flush, hypotension, and headache to histamine. The addition of histamine to treatment with IL-2 significantly enhanced the accumulation of CD25+ T cells in peripheral blood as compared to treatment with IL-2 alone (P< 0.003). Five patients remain in complete remission at 9, 18, 21, 24 and 26 months; the two patients in CR3 relapsed after 8 and 33 months, respectively. In the five patients with earlier relapse, the duration of remission after treatment with histamine/IL-2 has in each case exceeded that of previous remissions. We conclude that (i) histamine and IL-2 synergize to kill human AML blasts in vitro, and (ii) histamine/IL-2 is a safe and feasible approach to immunotherapy of AML which merits further investigation.

Adult↗
PubMed1996

NK cell-mediated killing of AML blasts: role of histamine, monocytes and reactive oxygen metabolites.

Blasts recovered from patients with acute myelogenous leukaemia (AML) were lysed by heterologous natural killer (NK) cells treated with NK cell-activating cytokines such as interleukin-2 (IL-2) or interferon-alpha (IFN-alpha). The cytokine-induced killing of AML blasts was inhibited by monocytes, recovered from peripheral blood by counterflow centrifugal elutriation. Histamine, at concentrations exceeding 0.1 microM, abrogated the monocyte-induced inhibition of NK cells; thereby, histamine and IL-2 or histamine and IFN-alpha synergistically induced NK cell-mediated destruction of AML blasts. The effect of histamine was completely blocked by the histamine H2-receptor (H2R) antagonist ranitidine but not by its chemical control AH20399AA. Catalase, a scavenger of reactive oxygen metabolites (ROM), reversed the monocyte-induced inhibition of NK cell-mediated killing of blast cells, indicating that the inhibitory signal was mediated by products of the respiratory burst of monocytes. It is concluded that (i) monocytes inhibit anti-leukemic properties of NK cells, (ii) the inhibition is conveyed by monocyte-derived ROM, and (iii) histamine reverses the inhibitory signal and, thereby, synergizes with NK cell-activating cytokines to induce killing of AML blasts.

CD56 Antigen↗
PubMed1996

Lymphoblastoid human interferon and low dose IL-2 combined with donor lymphocyte infusion as therapy of a third relapse of CML--a case report.

A patient, who was treated twice with donor lymphocyte infusions for relapse of CML after an allogeneic BMT was given lymphoblastoid human alpha-IFN after a third relapse. Further donor lymphocyte infusions were followed by repeated courses of 30 days treatment with a low dosage of IL-2 subcutaneously, alternately with alpha-IFN. This treatment resulted in a hematologic and cytogenetic remission. He also developed a limited degree of chronic GVHD. At the latest follow-up at 20 months after the third course of lymphocyte infusions he is in continuous hematologic and cytogenetic remission. Furthermore, a qualitative PCR analysis for the bcr/abl translocation is negative.

Adult↗
PubMed1995

Kinetics of inorganic phosphate release during the interaction of p21ras with the GTPase-activating proteins, p120-GAP and neurofibromin.

The rate of GTP hydrolysis on p21ras is accelerated by approximately 10(5) times by the catalytic domains of GTPase-activating proteins (GAPs), p120-GAP (GAP-344) or neurofibromin (NF1-334). The kinetic mechanism of this activation has been investigated by following the release of inorganic phosphate (Pi), using a fluorescent probe that is sensitive to Pi [Brune, M., Hunter, J., Corrie, J. E. T., & Webb, M. R. (1994) Biochemistry 33, 8262-8271]. Measurements were made in real time with a stopped-flow apparatus, in which the p21ras complex with the 2',3'-methanthraniloyl analogue of GTP (mantGTP) was mixed with the GAP in the presence of this Pi probe. The results show that Pi release is fast and that the overall hydrolysis is controlled by the cleavage itself or a conformational change preceding the cleavage. The time courses were single exponentials over a range of [GAP-344] and were modeled to show that a single step controlled Pi release. The maximum rate constant was 15 s-1 (all data at 30 degrees C, pH 7.6, low ionic strength) in experiments in which GAP-344 underwent a single turnover, compared with 5 s-1 for multiple-turnover experiments, and possible causes of this discrepancy were investigated and discussed. With NF1-334 the time courses were more complex, showing a lag prior to rapid release of Pi. The results were consistent with a Kd of 0.04 microM for NF1-344 affinity is some 3 orders of magnitude tighter than that of GAP-344.(ABSTRACT TRUNCATED AT 250 WORDS)

Escherichia coli↗
PubMed1995

Strontium chloride Sr 89 for treating pain from metastatic bone disease.

The role of strontium chloride Sr 89 in the palliative treatment of pain associated with metastatic bone disease is reviewed. Conventional therapies to relieve metastatic bone pain include nonopioid and opioid analgesics, hormonal therapy, external-beam irradiation, and chemotherapy. Limitations in the long-term safety and effectiveness of these treatments have increased interest in using systemic radioactive isotopes for palliation of pain. Strontium chloride Sr 89 is a relatively new bone-seeking radiopharmaceutical that has FDA-approved labeling for use in relieving pain associated with skeletal metastases. An analogue of calcium, strontium chloride Sr 89 is rapidly cleared from the blood after i.v. injection. The agent selectively irradiates metastatic sites while generally sparing normal soft-bone tissue. In clinical studies, a majority of patients with prostate or breast cancer obtained substantial relief from bone pain after receiving strontium chloride Sr 89 alone or in combination with external-beam irradiation. Adverse effects tend to be mild, but patients should be monitored for possible hematologic toxicity. Patients should discontinue any calcium-containing products before receiving the agent. The typical dose is 4 mCi (148 MBq) administered by slow i.v. push over one to two minutes; doses can be repeated at three-month intervals. Pain relief usually begins in 10-20 days and lasts up to six months. Radiation safety measures are necessary in handling strontium chloride Sr 89 and the wastes of patients. Strontium chloride Sr 89 is costly, but preliminary analysis indicates that it may reduce management expenditures overall.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Neoplasms↗
PubMed1995

Time resolved measurements show that phosphate release is the rate limiting step on myofibrillar ATPases.

The myofibril is a good model to study the ATPase of the muscle fibre. When myofibrillar ATPase reaction mixtures are quenched in acid, there is a burst of Pi formation, due to AM.ADP.Pi or Pi, as shown in the scheme: AM+ATP<-->A.M.ATP<-->AM.ADP.Pi<-->AM.ADP+Pi<-->AM+ADP. Therefore, in the steady state, either AM.ADP.Pi or AM.ADP or both predominate. To determine which, we studied the reaction using a Pi binding protein (from E. coli) labeled with a fluorophore such that it is specific and sensitive to free Pi [Brune, M. et al. (1994) Biochemistry 33, 8262-8271]. We show that the Pi bursts with myofibrillar ATPases (calcium-activated or not, or crosslinked) are due entirely to protein bound Pi. Thus, with myofibrillar ATPases the AM.ADP.Pi state predominates.

Actins↗
PubMed1995

Pathway of processive ATP hydrolysis by kinesin.

Direct measurement of the kinetics of kinesin dissociation from microtubules, the release of phosphate and ADP from kinesin, and rebinding of kinesin to the microtubule have defined the mechanism for the kinesin ATPase cycle. The processivity of ATP hydrolysis is ten molecules per site at low salt concentration but is reduced to one ATP per site at higher salt concentration. Kinesin dissociates from the microtubule after ATP hydrolysis. This step is rate-limiting. The subsequent rebinding of kinesin-ADP to the microtubule is fast, so kinesin spends only a small fraction of its duty cycle in the dissociated state. These results provide an explanation for the motility differences between skeletal myosin and kinesin.

Adenosine Diphosphate↗
PubMed1995

A new method for the time-resolved measurement of phosphate release in permeabilized muscle fibers.

A new method for the measurement of phosphate release in contracting and relaxed permeabilized muscle fibers is described. The assay is based on a genetically engineered phosphate-binding protein labeled with a coumarin fluorescent probe, which binds inorganic phosphate tightly and shows a fourfold increase in fluorescence upon binding. Measurements of Pi release on the millisecond time scale with sensitivity in the 10 microM range are obtained that provide new information about the relationship between ATP hydrolysis and force production.

Adenosine Triphosphate↗
PubMed1994

Direct, real-time measurement of rapid inorganic phosphate release using a novel fluorescent probe and its application to actomyosin subfragment 1 ATPase.

A probe has been developed that can rapidly measure micromolar concentrations of inorganic phosphate (Pi), in particular to follow the release of Pi in real time from enzymes such as phosphatases. Its application is described to investigate the mechanism of actomyosin subfragment 1 ATPase. The probe uses the A197C mutant of Escherichia coli phosphate binding protein (PBP), generated by oligonucleotide-directed mutagenesis. A new fluorophore, N-[2-(1-maleimidyl)ethyl]-7-(diethylamino)coumarin-3-carboxamide (MDCC), was attached to the single cysteine to produce the reporter molecule that was purified free of unlabeled protein and unattached MDCC. The labeled protein has an excitation maximum at 425 nm and emission maximum at 474 nm in the absence of Pi, shifting to 464 nm with a 5.2-fold increase in fluorescence (lambda max/lambda max) when complexed with Pi at pH 7.0, low ionic strength, 22 degrees C. The fluorescence increase is not much altered by change to pH 8 or by increase in ionic strength to 1 M. Pi binds tightly (Kd approximately 0.1 microM) and rapidly (1.36 x 10(8) M-1 s-1) and the dissociation rate constant is 21 s-1, at pH 7.0, low ionic strength, 22 degrees C. A variety of phosphate esters were tested to investigate the specificity of the MDCC-PBP and none gave a significant fluorescence increase at 100 microM or higher concentration. ATP weakly inhibited the Pi-induced fluorescence change, indicating that it binds at least 3000-fold weaker than Pi. Because Pi is a widespread contaminant, the probe is used in conjunction with a "Pi mop", consisting of 7-methylguanosine and purine nucleoside phosphorylase, to remove free Pi from solutions by its conversion to ribose 1-phosphate. Because the equilibrium constant of this reaction is > 100, free Pi can be reduced below 0.1 microM. The probe was used to measure the rate of Pi release during a single turnover of ATP hydrolysis with actomyosin subfragment 1 from rabbit skeletal muscle, to determine to what extent Pi release contributes to the rate limitation of this ATPase. Using a stopped-flow apparatus, a small lag prior to rapid Pi release was detected at pH 7.0, low ionic strength, between 5 and 22 degrees C at both high and low [ATP]. For measurements of a single turnover at low [ATP], the observed rate increased with [actin], showing saturation with a Km with respect to actin of 26 microM.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenosine Triphosphate↗
PubMed1994

Haemoglobin Köln as de novo mutations in Sweden: diagnosis by PCR and specific enzymatic cleavage.

Three independent cases of chronic haemolytic anaemia in Sweden have recently been demonstrated to be due to the unstable haemoglobin variant Hb Köln. The patients, all of whom have partially compensated chronic haemolytic anaemia, presented with aggravated haemolysis during acute infections in childhood. In one case, acute B19 parvovirus infection induced an aplastic crisis. The substitutions all seem to have occurred as de novo mutations. Diagnosis was based on haemoglobin instability testing and isoelectric focusing of haemoglobin dimers. The final identification procedure for the substitutions included extraction of DNA from whole blood, polymerase chain reaction (PCR) amplification of parts of the beta-globin gene and nucleotide sequencing of the resulting material, or studies of restriction length polymorphisms (RFLPs) using the restriction endonucleases Mae II or Nla III. The use of PCR-RFLP is recommended as a valuable tool for diagnosing Hb Köln.

Adult↗
PubMed1994

Receptor interactions of Abbott-81988, a highly potent, non-peptide angiotensin-II antagonist selective for type-1 receptors.

Abbott-81988 (A-81988) was selected from a series of related compounds as a highly potent and selective antagonist of angiotensin receptors. In the rabbit aorta, A-81988 exhibited a pA2 of 10.12 (+/- 0.08) vs. angiotensin-II, for type 1 receptors (AT1), and the antagonism appeared competitive. These results agreed with radioligand assays in which A-81988 inhibited the binding of [125I]-Sar1-Ile8-Angiotensin-II to rat liver membranes with a pKI of 9.12 (+/- 0.63). A-81988 was selective for AT1 receptors based on its lack of activity at other sites, such as aortic alpha 1 receptors. Moreover, A-81988 lacked affinity for AT2 receptors of bovine cerebellar membranes or for alpha or beta adrenergic receptors in binding assays. A-81988 lowered blood pressure significantly in vivo in renal artery-ligated rats at doses of 0.3 mg/kg administered either i.v. or p.o. The compound was rapidly and almost completely absorbed from the duodenum of anesthetized rats and demonstrated very low first-pass metabolism in the rat liver. These properties of selectivity toward and potency for antagonizing AT1 receptors, activity in lowering blood pressure in experimental animals, and favorable pharmacokinetic properties indicate that A-81988 should be a useful antihypertensive agent in man.

Angiotensin II↗
PubMed1993

Pharmacological characterization of Abbott-81282, a novel, non-peptide angiotensin-II antagonist selective for type-1 receptors.

Abbott-81282 (A-81282) has been identified among a series of related compounds as being a highly potent and selective antagonist of angiotensin receptors. At AT1 receptors of the rabbit aorta, A-81282 exhibited a pA2 of 9.64 (+/- 0.33) vs. angiotensin-II, and demonstrated characteristics consistent with competitive antagonism of this receptor. These results were supported in radioligand binding assays in which A-81282 inhibited the binding of [125I]-Sar-Il8-Angiotensin-II to rat liver membranes with a pKI of 8.505 (+/- 0.102). Selectivity of this agent for AT1 receptors was validated by its lack of activity at other receptor sites, such as alpha 1 receptors of isolated rabbit aorta. Moreover, A-81282 lacked affinity for AT2 receptors of bovine cerebellar membranes or for alpha or beta adrenergic receptor sites in radioligand binding assays. A-81282 lowered blood pressure significantly in vivo in renal artery-ligated rats at doses of 1 mg/kg i.v. or 5 mg/kg p.o. The compound was slowly and moderately absorbed from the duodenum of anesthetized rats and demonstrated low first-pass metabolism in the rat liver. Because of its selectivity and potency for antagonizing AT1 receptors, and its activity in lowering blood pressure in experimental animals, A-81282 has the potential to be a useful antihypertensive agent in man.

Angiotensin Receptor Antagonists↗