Radiosensitization by BRAF inhibitor therapy-mechanism and frequency of toxicity in melanoma patients.

BACKGROUND: Recent evidence suggests that ionizing radiation may be associated with unexpected side-effects in melanoma patients treated with concomitant BRAF inhibitors. A large multicenter analysis was carried out to generate reliable safety data and elucidate the mechanism. METHODS: A total of 161 melanoma patients from 11 European skin cancer centers were evaluated for acute and late toxicity, of whom 70 consecutive patients received 86 series of radiotherapy with concomitant BRAF inhibitor therapy. To further characterize and quantify a possible radiosensitization by BRAF inhibitors, blood samples of 35 melanoma patients were used for individual radiosensitivity testing by fluorescence in situ hybridization of chromosomal breaks after ex vivo irradiation. RESULTS: With radiotherapy and concomitant BRAF inhibitor therapy the rate of acute radiodermatitis ≥2° was 36% and follicular cystic proliferation was seen in 13% of all radiotherapies. Non-skin toxicities included hearing disorders (4%) and dysphagia (2%). Following whole-brain radiotherapy, rates of radiodermatitis ≥2° were 44% and 8% (P < 0.001) for patients with and without BRAF inhibitor therapy, respectively. Concomitant treatment with vemurafenib induced acute radiodermatitis ≥2° more frequently than treatment with dabrafenib (40% versus 26%, P = 0.07). In line with these findings, analysis of chromosomal breaks ex vivo indicated significantly increased radiosensitivity for patients under vemurafenib (P = 0.004) and for patients switched from vemurafenib to dabrafenib (P = 0.002), but not for patients on dabrafenib only. No toxicities were reported after stereotactic treatment. CONCLUSION: Radiotherapy with concomitant BRAF inhibitor therapy is feasible with an acceptable increase in toxicity. Vemurafenib is a more potent radiosensitizer than dabrafenib.

[The surgeon's role as expert witness in malpractice lawsuits. Purpose and requirements of legal medical opinions]. / Der Chirurg als Sachverständiger in der gerichtlichen Auseinandersetzung über Behandlungsfehler. Voraussetzungen, Anforderung, Aufgaben aus ärztlicher Sicht.

Even experienced medical advisors need clear guidelines on the extent and form of expert opinions presented to courts of law. The importance of thorough document study, correctly organizing findings, and carefully weighing the various factors influencing an opinion cannot be stressed enough. Presented here is a sample opinion for German civil court trials at the state level. It illustrates how best to combine research and clinical results, personal professional experience, and citations from the literature to structure legally valid evidence in the form of an expert opinion. The importance of cogent response to examiners' and cross-examiners' questions is demonstrated, as are differences between civil and criminal proceedings. An appendix cites the appropriate passages from the German legal code concerning remuneration for expert opinions.

Second-generation peptidomimetic inhibitors of protein farnesyltransferase demonstrating improved cellular potency and significant in vivo efficacy.

The synthesis and evaluation of analogues of previously reported farnesyltransferase inhibitors, pyridyl benzyl ether 3 and pyridylbenzylamine 4, are described. Substitution of 3 at the 5-position of the core aryl ring resulted in inhibitors of equal or less potency against the enzyme and decreased efficacy in a cellular assay against Ras processing by the enzyme. Substitution of 4 at the benzyl nitrogen yielded 26, which showed improved efficacy and potency and yet presented a poor pharmacokinetic profile. Further modification afforded 30, which demonstrated a dramatically improved pharmacokinetic profile. Compounds 26 and 29 demonstrated significant in vivo efficacy in nude mice inoculated with MiaPaCa-2, a human pancreatic tumor-derived cell line.

New antimitotic agents with activity in multi-drug-resistant cell lines and in vivo efficacy in murine tumor models.

During a screen for compounds that could inhibit cell proliferation, a series of new tubulin-binding compounds was identified with the discovery of oxadiazoline 1 (A-105972). This compound showed good cytotoxic activity against non-multi-drug-resistant and multi-drug-resistant cancer cell lines, but its utility in vivo was limited by a short half-life. Medicinal chemistry efforts led to the discovery of indolyloxazoline 22g (A-259745), which maintained all of the in vitro activity seen with oxadiazoline 1, but also demonstrated a better pharmacokinetic profile, and dose-dependent in vivo activity. Over a 28 day study, indolyloxazoline 22g increased the life span of tumor-implanted mice by up to a factor of 3 upon oral dosing. This compound, and others of its structural class, may prove to be useful in the development of new chemotherapeutic agents to treat human cancers.

3,5-Bis(trifluoromethyl)pyrazoles: a novel class of NFAT transcription factor regulator.

A series of bis(trifluoromethyl)pyrazoles (BTPs) has been found to be a novel inhibitor of cytokine production. Identified initially as inhibitors of IL-2 synthesis, the BTPs have been optimized in this regard and even inhibit IL-2 production with a 10-fold enhancement over cyclosporine in an ex vivo assay. Additionally, the BTPs show inhibition of IL-4, IL-5, IL-8, and eotaxin production. Unlike the IL-2 inhibitors, cyclosporine and FK506, the BTPs do not directly inhibit the dephosphorylation of NFAT by calcineurin.

Conditioning of drug-induced immunomodulation in human volunteers: a European collaborative study.

Although several studies on conditioning of the immune system in animals have been published, no comparable data on human research have been available in the past. The present paper presents results of conditioning studies in volunteers performed in two research centres, namely the University of Trier (Germany) and the University of Utrecht (The Netherlands). After administration of a neutral stimulus (conditioned stimulus: CS), subjects were injected with epinephrine (unconditioned stimulus) for three or four days (depending on study). Subcutaneous injection of epinephrine caused a rapid enhancement of the activity of natural killer cells (NKCA) in venous blood, which was chosen as the unconditioned response. On the test trial, when saline instead of epinephrine was injected, the Trier group found a conditional enhancement of NKCA. No changes in NKCA were found in the control subjects, who received saline injections on all days along with the CS. The Utrecht group tried to replicate these results using a slightly different design. After obtaining non-confirmative results, the Utrecht experimenters tried to parallel the experimental settings of the Trier group as closely as possible. However, once again they failed to replicate the results of the Trier group. Possible reasons for the different results obtained in the two research groups are discussed.

Oral health of representative samples of Germans examined in 1989 and 1992.

This paper presents selected results of two recent representative cross sectional studies of oral health in the German population, conducted by the IDZ (Institute of German Dentists) for the old Federal States (the former Federal Republic of Germany) in 1989 (n= 1741) and the new Federal States (the former German Democratic Republic) in 1992 (n=1519). Each epidemiological study reported both clinical and sociological data. The following average DMFT values were determined: for the children aged 8/9 yr: 1.4; for the adolescents aged 13/14 yr: 4.9; for the adults aged 35-44 yr: 16.1; and for the adults aged 45-54 yr: 17.9. These are the overall averages for "Germany West" and "Germany East" combined. The overall results for periodontal health in adults were as follows: CPITN 0: 4.9%; CPITN 1:11.2%; CPITN 2: 24.6%; CPITN 3: 42.7%; and CPITN 4:16.6% for the adults aged 35-44 yr and CPITN 0: 2.4%; CPITN 1: 8.1%; CPITN 2: 20.4%; CPITN 3: 46.8%; and CPITN 4: 22.3% for the adults aged 45-54 yr. The following average tooth loss figures were calculated for Germany as a whole: age group 35-44 yr: 3.9 missing teeth; age group 45-54 yr: 7.7 missing teeth. In addition, all the morbidity data determined have been analysed for statistical significance in the comparison between "West" and "East" Germany. The prevalences presented are also differentiated according to the socioeconomic status (SES) of the subjects, with the lower social strata as a whole showing higher morbidity prevalences. Comparisons show that caries has declined significantly among children and adolescents in Germany in the last 10-15 yr. Finally, the authors recommend the inclusion of qualitative research techniques when studying the differential causation of the inverse correlation between oral morbidity and social status.

Variety of muscle responses to tactile stimuli.

Influences exerted by tactile stimuli on the muscle activity were investigated with two methods: (1) analysis of kinematics and electromyographic (EMG) activity of eight forelimb muscles during contact placing (CP) reactions elicited by tactile stimuli applied to the dorsal, medial or lateral sides of the paw in cats, and (2) the Hoffmann (H)-reflex technique to quantify the effects of the tactile stimuli on the excitability of the alpha motoneurones of the soleus muscle in awake rats. The first group of the data showed that the tactile stimuli applied to dorsal, medial or lateral aspects of the paw led to different strategies of the forelimb movements during CP reactions. These differences arose from various patterns of activation of the elbow flexor and extensor muscles at the beginning of CP reactions and a various involvement of the medio-lateral components of movements, depending on the site of the tactile stimulus application. With the H-reflex technique it was found that the tactile stimulus diminished the excitability of alpha motoneurones of the soleus muscle when applied to the skin overlying the lateral side of the ankle joint. This effect was in line with the observation that the tactile stimulus applied to the lateral side of the paw activated the elbow flexor muscles but not their antagonists to initiate CP reaction.

Various strategies of forelimb movement during contact placing reactions elicited by tactile stimulation of the different aspects of a cat's paw.

Forelimb trajectory and the activity of eight muscles operating at the elbow, wrist and digit joints were analyzed during contact placing (CP) reactions elicited by tactile stimuli applied to the lateral (L) or medial (M) side of the cat's forepaw to verify whether a common movement strategy was used in these reactions. A tactile stimulus applied to the lateral side of the paw led, most frequently, to a short-latency activation of the elbow flexor muscles and flexor carpi radialis. Stimulation of the medial side of the paw produced either a short-latency activation of the elbow flexors or both the elbow flexor and extensor muscles. At the distal joints it most frequently activated extensor carpi ulnaris and flexor carpi radialis muscles. Different patterns of activation of the muscles during LCP and MCP reactions led to a diverse involvement of elbow flexion and extension movements at the beginning of the reactions. LCP was usually initiated by the elbow flexion movement whereas during MCP reactions the elbow flexion often appeared with a delay due to a brief co-contraction of the elbow flexor and extensor muscles which temporarily locked the elbow joint. The latter reaction was initiated by a backward/upward movement at the proximal joints accompanied by an ulnar deviation and a palmar flexion of the paw. The medio-lateral components of the movement were also clearly different in LCP and MCP reactions, both at the proximal and distal joints. The results indicate that various strategies of movement are used in CP reactions depending on the site of tactile stimulation.

Activity of elbow flexor and extensor muscles during contact placing reaction in the cat.

Activity of the biceps brachii and of the lateral head of the triceps brachii was recorded in cats during contact placing reaction evoked by tactile stimulation of the dorsum of the forepaw. Chronically implanted electrodes were used for this purpose. Two patterns of responses were observed. In the first pattern the two muscles were activated alternately while in the second pattern they were coactivated during the first phase of the reaction. Activity of the biceps brachii preceded that of the triceps brachii in both patterns. The second pattern resembled the pattern of responses of elbow flexors and extensors to mechanical stimuli applied to the dorsum of the forelimb during locomotion.

Activity of the elbow flexor and extensor muscles during contact placing elicited by tactile stimulation of various aspects of the forelimb in the cat.

The activity of the biceps brachii and lateral head of the triceps brachii were compared during the contact placing reactions elicited by tactile stimuli applied to the lateral, medial or dorsal aspects of the forepaw to verify the hypothesis that common movement strategy was used in all these reactions. Similar latencies and patterns of muscle activation have been found for the medial and dorsal placing while the different timing of the muscle activation was seen in lateral placing reactions. Both muscles often coactivated during lateral or dorsal and less frequently during medial placing reactions. In dorsal placing the coactivations predominated at the beginning of the reactions while in lateral placing they appeared most frequently in later phases of the reaction. The co-contraction of the elbow flexor and extensor muscles leads to locking of the elbow joint. Thus, the coactivation of these muscles in different phases of the lateral, medial and dorsal placing reactions indicates that various movement strategies have been used as the elbow flexion movement is initiated in different phases of these reactions.

Locomotion induces changes in Trk B receptors in small diameter cells of the spinal cord.

INTRODUCTION AND METHODS: Locomotor training leads to improvement of stepping ability in animals after spinal cord transection (1). Recent data point to neurotrophins as possible factors involved in this improvement. Motoneurones synthesising BDNF, NT-4 and NT-3 are a potent source of neurotrophins for the spinal network (2, 3). Physical exercise increases BDNF neurotrophin gene expression in the rat hippocampus (4). If exercise enhances BDNF expression also in the spinal cord, upregulation of its receptor Trk B may occur. To verify this hypothesis we tested whether exercise influences TrkB receptor system in the spinal cord. Six adult, male Wistar rats walked on the treadmill five days a week, 1,000 m daily with the speed of 20 to 25 cm/s. After 4 weeks of training animals were anaesthetised with pentobarbital sodium (80 mg/kg b.w.) and perfused with 0.01 M PBS followed by 2% paraformaldehyde and 0.2% parabenzoquinone in 0.1 M PB. Three non-trained animals were used as controls. Cryostat 40 microns sections were processed free-floating with TrkB polyclonal antibody (1:1,000, Santa Cruz) and ABC Vectastain detection system. Sections were examined under Nikon light microscope and analysed with Image-Pro Plus 4 software. RESULTS AND DISCUSSION: TrkB immunoreactivity (IR) was detected in number of spinal cells at the lumbar level in non-trained animals (Fig. 1A). The strongest IR appeared in the perikarya and processes of small diameter cells rarely scattered in the grey and white matter. The average area of these cells was 50 micron 2 (+/- 10). Exercise increased by over 50% the number of TrkB immunostained small cells (Fig. 1B). An enhancement of perikaryonal immunostaining of these cells was also observed (Fig. 1B, inset). Testing the identity of Trk B IR small diameter cells did not prove their astroglial (GFAP IR) and gabaergic (GAD IR) phenotype in the grey matter. Some of TrkB IR cells in the white matter were astrocytes. Our data point to physical exercise as a potent method to make spinal cells more receptive to neurotrophic stimuli.

Evaluation of the oral antimitotic agent (ABT-751) in dogs with lymphoma.

BACKGROUND: ABT-751 is a novel orally available antimitotic agent that targets microtubule polymerization. This mechanism may suggest potential activity in canine lymphoma. OBJECTIVE: Determine a maximum tolerated dose for ABT-751, and assess long-term tolerability and activity in canine lymphoma. ANIMALS: Thirty dogs with newly diagnosed (n = 19) or relapsed (n = 11) non-Hodgkin's lymphoma. METHODS: Dogs (n = 11) were enrolled in a rapid dose escalation study to define the maximum tolerated dose. Upon definition of a maximally tolerated dose, a cohort expansion of 19 dogs allowed verification of long-term tolerability and assessment of activity. Study endpoints in the cohort expansion included chronic tolerability, response rate, response duration, and time to progression. Additional endpoints included serum pharmacokinetics, lymph node drug concentrations, and changes in circulating endothelial cells. RESULTS: The maximum tolerated dose of ABT-751 was 350 mg/m(2) PO q24h. Dose-limiting toxicities included vomiting and diarrhea, which resolved with a schedule adjustment to 350 mg/m(2) PO q48h. ABT-751 was consistently detected in lymphoma tissue samples from dogs treated at or above the maximum tolerated dose. In the cohort expansion, objective responses were seen in 3/15 (20%) dogs with a response duration ranging from 21 to 111 days. Decreases in circulating endothelial cells were seen in 10 dogs at day 7 (2 responding dogs and 8 nonresponding dogs). CONCLUSION: ABT-751 was well tolerated at 350 mg/m(2) PO q24h for 7 days and then q48h thereafter. Activity of ABT-751 suggested a rationale for additional studies of ABT-751 as part of a combination chemotherapy protocol for lymphoma or other canine cancers.

Use of the H3 receptor antagonist radioligand [3H]-A-349821 to reveal in vivo receptor occupancy of cognition enhancing H3 receptor antagonists.

BACKGROUND AND PURPOSE: The histamine H3 receptor antagonist radioligand [3H]-A-349821 was characterized as a radiotracer for assessing in vivo receptor occupancy by H3 receptor antagonists that affect behaviour. This model was established as an alternative to ex vivo binding methods, for relating antagonist H3 receptor occupancy to blood levels and efficacy in preclinical models. EXPERIMENTAL APPROACH: In vivo cerebral cortical H3 receptor occupancy by [3H]-A-349821 was determined in rats from differences in [3H]-A-349821 levels in the isolated cortex and cerebellum, a brain region with low levels of H3 receptors. Comparisons were made to relate antagonist H3 receptor occupancy to blood levels and efficacy in a preclinical model of cognition, the five-trial inhibitory avoidance response in rat pups. KEY RESULTS: In adult rats, [3H]-A-349821, 1.5 microg x kg(-1), penetrated into the brain and cleared more rapidly from cerebellum than cortex; optimally, [3H]-A-349821 levels were twofold higher in the latter. With increasing [3H]-A-349821 doses, cortical H3 receptor occupancy was saturable with a binding capacity consistent with in vitro binding in cortex membranes. In studies using tracer [3H]-A-349821 doses, ABT-239 and other H3 receptor antagonists inhibited H3 receptor occupancy by [3H]-A-349821 in a dose-dependent manner. Blood levels of the antagonists corresponding to H3 receptor occupancy were consistent with blood levels associated with efficacy in the five-trial inhibitory avoidance response. CONCLUSIONS AND IMPLICATIONS: When employed as an occupancy radiotracer, [3H]-A-349821 provided valid measurements of in vivo H3 receptor occupancy, which may be helpful in guiding and interpreting clinical studies of H3 receptor antagonists.

Different effect of locomotor exercise on the homogenate concentration of amino acids and monoamines in the rostral and caudal lumbar segments of the spinal cord in the rat.

STUDY DESIGN: The effect of long-term (4 weeks) moderate locomotor exercise on segmental distribution of glutamate (Glu), aspartate, gamma-aminobutyric acid, glycine (Gly), serotonin and noradrenaline in the spinal cord of adult rats was investigated. OBJECTIVES: In light of the data showing modulation of some neurotransmitters in the low-lumbar segments of the rat due to physical exercise, our aim was to establish how segmentally specific is this effect with respect to neuroactive amino acids and monoamines. SETTING: Laboratory of Reinnervation Processes, Department of Neurophysiology, Nencki Institute of Experimental Biology, Warsaw, Poland. METHODS: Amino acids and monoamines content was measured by means of HPLC in the whole tissue homogenate of the spinal cord in nonexercised and exercised rats. RESULTS: Glu and Gly homogenate concentration was the highest among all tested compounds. There was an intersegmental rostro-caudal gradient of concentration of neuroactive amino acids and monoamines, progressing caudally. Exercise modified this gradient exerting opposite effect on their concentration of amino acids and monoamines in the rostral and caudal lumbar segments. CONCLUSION: Locomotor exercise leads to neurochemical remodeling of the spinal cord, which is differently manifested in the rostral and caudal lumbar segments of the spinal cord.