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Michael Adler

Publications and source records attributed to Michael Adler.

30 records · Page 2Linked to original sources
PubMed2003

Detection of rViscumin in plasma samples by immuno-PCR.

To allow for pharmacokinetic studies in adjunction with the current clinical developments of the potent cytostatic anti-cancer drug rViscumin, a sandwich immuno-PCR (IPCR) assay was developed for the detection of rViscumin in blood plasma. The IPCR was carried out with a commercially available reagent kit, consisting of pre-assembled rViscumin-specific antibody-DNA conjugates as well as a specific competitor DNA fragment to be amplified by PCR. Various combinations of capture- and detection-antibodies were compared for performance in IPCR. Using the optimized assay, as few as 50 zeptomol (approx. 100 fg/ml) rViscumin (MW 57 kDa) was detectable in standardized human serum samples. The IPCR assay was very selective for rViscumin and in spiking experiments in proband plasma samples, signal recovery rates between 70% and 120% were obtained. The linear sensitivity range of the assay covered more than five orders of magnitude. Repeated measurements of rViscumin resulted in a mean standard deviation value of 14.2%.

Animals↗
PubMed2003

Monte Carlo simulation of the assembly of bis-biotinylated DNA and streptavidin.

We present Monte Carlo simulations of the self-assembly of bivalent bis-biotinylated DNA molecules with the tetravalent biotin-binding protein streptavidin (STV). By fitting the STV binding probabilities for the four possible valencies, the modelling correctly reproduces the dependencies of various network parameters experimentally observed in an earlier study. The combined results from the experimental and theoretical studies suggest that the binding probability for divalent STV formation is about 50 times larger than for the formation of trivalent and about 200 times larger than for tetravalent STV. In accordance with the experimental results, the modelling also indicates that the mixture of an equimolar ratio of DNA and STV leads to a maximum in size of the oligomeric DNA-STV clusters formed. Furthermore, we found a percolation transition in which the DNA cluster size increases rapidly with increasing DNA concentration resulting in the formation of a single supercluster at elevated concentrations. This behaviour coincides with the occurrence of an immobile band previously observed in electrophoretic experiments, indicating the formation of extremely large DNA-STV aggregate networks.

Biotinylation↗
PubMed2003

New considerations for an overall approach to treat hepatocellular carcinoma in cirrhotic patients.

BACKGROUND: Increasing numbers of cases and organ shortage justify reconsidering the global therapeutic approach for hepatocelluar carcinoma in cirrhotic patients. METHODS: Recent literature was reviewed, focused on new therapeutic technologies such as radiofrequency. RESULTS: For small tumors, liver transplantation offers theoretically the best chance for cure. However, organ shortage may eliminate this advantage, because of tumor progression while waiting for a graft. For small tumors, arising on compensated cirrhosis, resection or radiofrequency ablation may provide efficient local tumor control without precluding subsequent transplantation in case of tumor recurrence and/or cirrhosis decompensation. CONCLUSIONS: For small tumors and compensated cirrhosis, resection or radiofrequency could represent acceptable first line treatments. In addition to permit safe and immediate tumor control, this strategy would allow a preferential redistribution of grafts to patients with decompensated cirrhosis in whom transplantation is the only possibility.

Carcinoma, Hepatocellular↗
PubMed2003

Inhibition of neurotransmitter release by peptides that mimic the N-terminal domain of SNAP-25.

Botulinum neurotoxin serotypes A and E (BoNT/A and BoNT/E) block neurotransmitter release by cleaving the 206-amino-acid SNARE protein, SNAP-25. For each BoNT serotype, cleavage of SNAP-25 results in the loss of intact protein, the production of an N-terminal truncated protein, and the generation of a small C-terminal peptide. Peptides that mimic the C-terminal fragments of SNAP-25 following BoNT/A or BoNT/E cleavage were shown to depress transmitter release in bovine chromaffin cells and in Aplysia buccal ganglion cells. Similarly, the N-terminal-truncated SNAP-25 resulting from BoNT/A or BoNT/E cleavage has been found to inhibit transmitter exocytosis in various systems. With one exception, however, the inhibitory action of truncated SNAP-25 has not been demonstrated at a well-defined cholinergic synapse. The goal of the current study was to determine the level of inhibition of neurotransmitter release by N-terminal BoNT/A- or BoNT/E-truncated SNAP-25 in two different neuronal systems: cholinergically coupled Aplysia neurons and rat hippocampal cell cultures. Both truncated SNAP-25 products inhibited depolarization-dependent glutamate release from hippocampal cultures and depressed synaptic transmission in Aplysia buccal ganglion cells. These results suggest that truncated SNAP-25 can compete with endogenous SNAP-25 for binding with other SNARE proteins involved in transmitter release, thus inhibiting neurotransmitter exocytosis.

Animals↗
PubMed2003

A capillary electrophoresis technique for evaluating botulinum neurotoxin B light chain activity.

Botulinum neurotoxin B (BoNT/B) produces muscle paralysis by cleaving synaptobrevin/vesicle-associated membrane protein (VAMP), an 18-kDa membrane-associated protein located on the surface of small synaptic vesicles. A capillary electrophoresis (CE) assay was developed to evaluate inhibitors of the proteolytic activity of BoNT/B with the objective of identifying suitable candidates for treatment of botulism. The assay was based on monitoring the cleavage of a peptide that corresponds to residues 44-94 of human VAMP-2 (V51) following reaction with the catalytic light chain (LC) of BoNT/B. Cleavage of V51 generated peptide fragments of 18 and 33 amino acids by scission of the bond between Q76 and F77. The fragments and parent peptide were clearly resolved by CE, allowing accurate quantification of the BoNT/B LC-mediated reaction rates. The results indicate that CE is suitable for assessing the enzymatic activity of BoNT/B LC.

Botulinum Toxins↗
PubMed2003

Predictive models of short- and long-term survival in patients with nonbiliary cirrhosis.

The limited number of donor organs has placed a burden on the medical community to improve patient selection and timing of liver transplantation (LT). We aim to evaluate short- and long-term survival of 124 consecutive patients with a diagnosis of nonbiliary cirrhosis. Seventeen clinical, biochemical, functional, and hemodynamic parameters were computed. Patient survival was evaluated in the short term (3 months) by logistic regression, and the predictive power of the model was evaluated using receiver operating characteristic curves and the log likelihood ratio. For the long-term (up to 5 years) prognosis, the Cox proportional model was used. During follow-up, 54 patients died and 20 patients underwent LT. In the short-term study, the Model for End-Stage Liver Disease score (including bilirubin level, international normalized ratio [INR], and creatinine level) was as predictive as our score, which contained only two independent indicators (bilirubin and creatinine levels). In the long-term study, three independent variables (albumin level, INR, and creatinine level) emerged from the Cox model, and patients were classified into three survival-risk groups according to a prognostic index (PI): -1.039 x albumin (grams per deciliter) + 1.909 x log(e) INR + 1.207 x log(e) serum creatinine (milligrams per deciliter). Survival probabilities at 1 and 5 years were 89% and 80%, 63% and 52%, and 23% and 10% with a low, medium, and high PI, respectively. The validation study using the split-sample technique and data from independent patients confirmed that a high PI (>-2.5) identifies patients with a poor prognosis within 5 years. We thus have shown and validated that risk for death at the short and long term of patients with nonbiliary cirrhosis can be predicted with great accuracy using models containing a few simple and easily obtained objective variables, and these survival models are useful tools in clinical decision making, especially in deciding to list patients for LT and prioritization on the liver waiting list.

Female↗
PubMed2002

Development of a delivery vehicle for intracellular transport of botulinum neurotoxin antagonists.

A targeted delivery vehicle (DV) was developed for intracellular transport of emerging botulinum neurotoxin (BoNT) antagonists. The DV consisted of the isolated heavy chain (HC) of BoNT/A coupled to a 10-kDa amino dextran via the heterobifunctional linker 3-(2-pyridylthio)-propionyl hydrazide. The HC served to target BoNT-sensitive cells and promote internalization of the complex, while the dextran served as a platform to deliver model therapeutic molecules to the targeted cells. To determine the ability of this chimeric glycoprotein to enter neurons, dextran and HC were labeled independently with the fluorescent dyes Oregon green 488 and Cy3, respectively. Internalization of DV was monitored in primary cortical cells using laser confocal microscopy. Incubation of cells for 24 h with DV resulted in discrete punctate labeling of both soma and processes. The Cy3 and Oregon green 488 signals were generally co-localized, suggesting that the complex remained in the same intracellular compartment during the initial 24 h. The DV-associated fluorescence was reduced progressively by co-application of increasing concentrations of unlabeled BoNT/A holotoxin. The results suggest that the BoNT/A HC is able to mediate internalization of a coupled dextran, even though the latter bears no resemblance to the BoNT/A light chain (LC). The HC of BoNT/A thus offers promise as a selective carrier to deliver BoNT antagonists to the nerve terminal cytoplasm for inhibiting the proteolytic activity of internalized BoNT/A LC.

Animals↗
PubMed2002

Genetic variation in morphine analgesic tolerance: a survey of 11 inbred mouse strains.

The present study assessed the analgesic potency of morphine in 11 inbred mouse strains before and after chronic morphine treatment. Using the 49 degrees C tail-withdrawal test, significant strain differences in morphine AD(50) estimates derived from cumulative dose-response curves were noted prior to tolerance induction on Day 1. AD(50) estimates were reassessed on Day 4, after three daily systemic morphine injections for 3 days using an escalating dose schedule (10, 20, and 40 mg/kg sc). In 9 of 11 strains, morphine potency was significantly reduced from 2-fold to as much as 11-fold. Two strains (129P3 and LP) displayed no evidence whatsoever of tolerance development. Neither initial baseline withdrawal latency nor morphine analgesic sensitivity was significantly correlated with tolerance magnitude. Also observed were strain-dependent alterations (mostly hyperalgesia) in baseline tail-withdrawal latencies as a result of chronic morphine treatment. The magnitude of hyperalgesia and analgesic tolerance was significantly correlated among strains, implicating common genetic substrates and supporting their proposed association. The present work demonstrates that the presence and magnitude of morphine analgesic tolerance is genotype-dependent and identifies strains with widely divergent liabilities that should facilitate identification of trait-relevant genes.

Analgesics, Opioid↗
PubMed2002

Supramolecular DNA-streptavidin nanocircles with a covalently attached oligonucleotide moiety.

Covalent hybrid conjugates consisting of streptavidin (STV) and a 24-mer single-stranded DNA oligonucleotide have been used as a starting material for the synthesis of supramolecular nanocircles. For this, the covalent hybrid conjugates were oligomerized by cross-linking with 5 ,5 -bis-biotinylated double-stranded DNA (dsDNA) fragments of various length. Heat denaturation of the resulting oligomeric conjugates and subsequent rapid cooling led to the formation of the nanocircles, in which the oligonucleotide-containing STV molecule is coupled with both ends of the circular bis-biotinylated dsDNA fragment. The circular structure of the bioconjugates was established by electrophoretic studies including Ferguson plot analysis as well as by scanning force microscopy (SFM) inspection. The formation process and the stability against degradation by ligand exchange with free D-biotin was compared for the nanocircles obtained from covalent oligonucleotide-STV hybrids and native STV. The former nanocircles revealed a decreased stability with respect to ring opening than the circles obtained from native STV. This suggested that the affinity of the covalent oligonucleotide-STV hybrid for binding biotinylated DNA is significantly decreased. Nevertheless, the single-stranded oligonucleotide moiety of the hybrid nanocircles can be used as a molecular handle for further functionalization. For instance, it was used for the selective DNA-directed immobilization at a surface, previously functionalized with complementary capture oligonucleotides. Moreover, we demonstrate that a pair of nanocircles, containing complementary oligonucleotide moieties, can be hybridized to form specific dimers, thereby generating a novel type of supramolecular DNA-protein nanostructures.

Base Sequence↗
PubMedDate not supplied

Cytotoxic actions of palytoxin on aortic smooth muscle cells in culture.

Palytoxin (PTX), isolated from a zoanthid of the genus Palythoa, is the most potent marine toxin known. Intoxication by PTX leads to vasoconstriction, hemorrhage, ataxia, muscle weakness, ventricular fibrillation, pulmonary hypertension, ischemia and death. In this study, clonal A7r5 rat aortic smooth muscle cells were used to study the mechanism of PTX-mediated cytotoxicity. A7r5 cells exposed to PTX for > or = 15 min exhibited surface granularities, vacuoles and rounding. These alterations culminated in a loss of viability as indicated by marked increases in the release of lactate dehydrogenase. Electrophysiological recording from A7r5 cells disclosed a profound membrane depolarization and an increase in conductance to Na+ and K+. PTX-mediated cytotoxicity could not be reversed by washout or by the addition of 10 microM verapamil but was antagonized by 100 microM ouabain or by removal of extracellular Na+ or Ca2+. In light of the involvement of vascular smooth muscle in PTX poisoning, A7r5 cells could serve as a useful model to test specific drugs for treatment of PTX intoxication.

Acrylamides↗
PubMedDate not supplied

Sex is dangerous.

Infectious diseases with high mortality, disability and creating public anxiety are not new, but despite this our initial responses to HIV/AIDS have been primitive and slow. Since the start of the epidemic over 60 million people throughout the world have been infected, with the main focus of the epidemic currently in Sub-Saharan Africa. However, there is every indication that the epidemic will move more towards South-East Asia, with increasing numbers in India and China. Infection with HIV has a profound effect on individuals and their families, and can also lead to destabilisation of societies through its effects on the economy, institutions and security. Considerable emphasis has been placed recently on the widespread use of anti-retroviral therapy. This is a worthwhile initiative but is only part of a balanced array of approaches, which requires building a political consensus, social economic interventions and modifying the biology. Strong political leadership is still required, with an approach that recognises that the socioeconomic drivers of this epidemic.

Acquired Immunodeficiency Syndrome↗