Prediction of Response to Immune Checkpoint Blockade in Patients with Metastatic Colorectal Cancer with Microsatellite Instability

BACKGROUND

Mismatch repair deficient (dMMR) tumors displaying microsatellite instability (MSI) represent a paradigm for the success of immune checkpoint inhibitor (ICI)-based immunotherapy, particularly in patients with metastatic colorectal cancer (mCRC). However, a proportion of patients with dMMR/MSI mCRC exhibit resistance to ICI. Identification of tools predicting MSI mCRC patient response to ICI are required for the design of future strategies further improving this therapy.

PATIENTS AND METHODS

We combined high-throughput DNA and RNA sequencing of tumors from 116 patients with MSI mCRC treated with anti-PD-1 +/- anti-CTLA-4 of the NIPICOL phase II trial (C1, NCT03350126, discovery set) and the IMMUNOMSI prospective cohort (C2, validation set). The DNA/RNA predictors whose status was significantly associated with ICI status of response in C1 were subsequently validated in C2. Primary endpoint was iPFS (progression-free survival by iRECIST).

RESULTS

Analyses showed no impact of previously suggested DNA/RNA indicators of resistance to ICI, e.g., MSISensor score, tumor mutational burden, or specific cellular and molecular tumoral contingents. By contrast, iPFS under ICI was shown in C1 and C2 to depend both on a multiplex MSI signature involving the mutations of 19 microsatellites (HR_C2 = 3.63; 95% CI [1.65-7.99] ; p = 1.4x10^-3) and the expression of a set of 182 RNA markers with a non-epithelial TGFB-related desmoplastic orientation (HR_C2 = 1.75 ; 95% CI [1.03-2.98] ; p = 0.035). Both DNA and RNA signatures were independently predictive of iPFS.

CONCLUSIONS

iPFS in patients with MSI mCRC can be predicted by simply analyzing the mutational status of DNA microsatellite-containing genes in epithelial tumor cells together with nonepithelial TGFB-related desmoplastic RNA markers.

Relevance of biopsy-derived pancreatic organoids in the development of efficient transcriptomic signatures to predict adjuvant chemosensitivity in pancreatic cancer

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Most patient with pancreatic cancer are treated by chemotherapy.

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Treatments selection are not personalized on the tumor characteristics.

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Signatures predicting chemotherapy efficiency are essential for personalizing treatments.

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An RNA signature of gemcitabine-sensitivity is developed leveraged on the dissimilarities between 2D and 3D in vitro models.

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Combining different in vitro models can help in defining clinically efficient transcriptomic signatures.

Pancreatic ductal adenocarcinoma (PDAC) patients are frequently treated by chemotherapy. Even if personalized therapy based on molecular analysis can be performed for some tumors, PDAC regimens selection is still mainly based on patients' performance status and expected efficacy. Therefore, the establishment of molecular predictors of chemotherapeutic efficacy could potentially improve prognosis by tailoring treatments. We have recently developed an RNA-based signature that predicts the efficacy of adjuvant gemcitabine using 38 PDAC primary cell cultures. While demonstrated its efficiency, a significant association with the classical/basal-like PDAC spectrum was observed. We hypothesized that this flaw was due to the basal-like biased phenotype of cellular models used in our strategy. To overcome this limitation, we generated a prospective cohort of 27 consecutive biopsied derived pancreatic organoids (BDPO) and include them in the signature identification strategy. As BDPO's do not have the same biased phenotype as primary cell cultures we expect they can compensate one with each other and cover a broader range of molecular phenotypes. We then obtained an improved signature predicting gemcitabine sensibility that was validated in a cohort of 300 resected PDAC patients that have or have not received adjuvant gemcitabine. We demonstrated a significant association between the improved signature and the overall and disease-free survival in patients predicted as sensitive and treated with adjuvant gemcitabine. We propose then that including BDPO along primary cell cultures represent a powerful strategy that helps to overcome primary cell cultures limitations producing unbiased RNA-based signatures predictive of adjuvant treatments in PDAC.

Morphological imaging and CT histogram analysis to differentiate pancreatic neuroendocrine tumor grade 3 from neuroendocrine carcinoma

PURPOSE

To compare morphological imaging features and CT texture histogram parameters between grade 3 pancreatic neuroendocrine tumors (G3-NET) and neuroendocrine carcinomas (NEC).

MATERIALS AND METHODS

Patients with pathologically proven G3-NET and NEC, according to the 2017 World Health Organization classification who had CT and MRI examinations between 2006-2017 were retrospectively included. CT and MRI examinations were reviewed by two radiologists in consensus and analyzed with respect to tumor size, enhancement patterns, hemorrhagic content, liver metastases and lymphadenopathies. Texture histogram analysis of tumors was performed on arterial and portal phase CT images. images. Morphological imaging features and CT texture histogram parameters of G3-NETs and NECs were compared.

RESULTS

Thirty-seven patients (21 men, 16 women; mean age, 56±13 [SD] years [range: 28-82 years]) with 37 tumors (mean diameter, 60±46 [SD] mm) were included (CT available for all, MRI for 16/37, 43%). Twenty-three patients (23/37; 62%) had NEC and 14 patients (14/37; 38%) had G3-NET. NECs were larger than G3-NETs (mean, 70±51 [SD] mm [range: 18 - 196mm] vs. 42±24 [SD] mm [range: 8 - 94mm], respectively; P=0.039), with more tumor necrosis (75% vs. 33%, respectively; P=0.030) and lower attenuation on precontrast (30±4 [SD] HU [range: 25-39 HU] vs. 37±6 [SD] [range: 25-45 HU], respectively; P=0.002) and on portal venous phase CT images (75±18 [SD] HU [range: 43 - 108 HU] vs. 92±19 [SD] HU [range: 46 - 117 HU], respectively; P=0.014). Hemorrhagic content on MRI was only observed in NEC (P=0.007). The mean ADC value was lower in NEC ([1.1±0.1 (SD)]×10^-3 mm²/s [range: (0.91 - 1.3)×10^-3 mm²/s] vs. [1.4±0.2 (SD)]×10^-3 mm²/s [range: (1.1 - 1.6)×10^-3 mm²/s]; P=0.005). CT histogram analysis showed that NEC were more heterogeneous on portal venous phase images (Entropy-0: 4.7±0.2 [SD] [range: 4.2-5.1] vs. 4.5±0.4 [SD] [range: 3.7-4.9]; P=0.023).

CONCLUSION

Pancreatic NECs are larger, more frequently hypoattenuating and more heterogeneous with hemorrhagic content than G3-NET on CT and MRI.

Sporadic pancreatic neuroendocrine tumor: Surgery of the primary tumor

The management of patients with sporadic pancreatic neuroendocrine tumors (PNET) is multi-disciplinary and often, multimodal. Surgery has a large part in treatment because it is the only potentially curative therapeutic modality if resection can be complete. The update reviews the operative indications and the different surgical techniques available (including parenchymal-sparing surgery) to treat the primary lesion according to patient status, preoperative work-up and whether the tumor is functioning or not. The place of observation for "small" non-functional sporadic PNET is also discussed.

Preoperative imaging and pathologic classification for pancreatic neuroendocrine tumors

The management of patients with pancreatic neuroendocrine tumor (PNET), whether hormonally secretory or not, is multidisciplinary and often multimodal. Surgical treatment plays a central role because complete resection is the only potentially curative treatment. The choice of the therapeutic plan for a PNET requires precise localization of the primary tumor (which may sometimes be multiple in case of genetic predisposition), confirmation of the diagnosis of PNET, a search for metastases (mainly hepatic), and identification of the main histoprognostic factors. This update focuses on the WHO 2017 histological classification and recent innovations in the preoperative assessment of PNET using conventional and isotopic imaging. The aim is to not only allow the mapping of primary and metastatic lesions but also to predict tumor aggressiveness.

A false postoperative recurrence of intraductal and papillary mucinous neoplasm of the pancreas

Stenosis of pancreatico-digestive anastomoses following pancreaticoduodenectomy is frequently observed. In a patient operated on for intraductal papillary and mucinous neoplasm, it can induce a massive dilatation of the main pancreatic duct leading to the misdiagnosis of tumor recurrence with main duct involvement.

MGMT expression predicts response to temozolomide in pancreatic neuroendocrine tumors

Temozolomide (TEM) showed encouraging results in well-differentiated pancreatic neuroendocrine tumors (WDPNETs). Low O(6)-methylguanine-DNA methyltransferase (MGMT) expression and MGMT promoter methylation within tumors correlate with a better outcome under TEM-based chemotherapy in glioblastoma. We aimed to assess whether MGMT expression and MGMT promoter methylation could help predict the efficacy of TEM-based chemotherapy in patients with WDPNET. Consecutive patients with progressive WDPNET and/or liver involvement over 50% who received TEM between 2006 and 2012 were retrospectively studied. Tumor response was assessed according to Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 guidelines. Nuclear expression of MGMT was assessed by immunochemistry (H-score, 0-300) and MGMT promoter methylation by pyrosequencing. Forty-three patients (21 men, 58years (27-84)) with grade 1 WDPNET (n=6) or 2 (n=36) were analyzed. Objective response, stable disease, and progression rates were seen in 17 patients (39.5%), 18 patients (41.9%), and 8 patients (18.6%), respectively. Low MGMT expression (≤50) was associated with radiological objective response (P=0.04) and better progression-free survival (PFS) (HR=0.35 (0.15-0.81), P=0.01). Disease control rate at 18months of treatment remained satisfying with an MGMT score up to 100 (74%) but dropped with a higher expression. High MGMT promoter methylation was associated with a low MGMT expression and longer PFS (HR=0.37 (0.29-1.08), P=0.05). Low MGMT score (≤50) appears to predict an objective tumor response, whereas an intermediate MGMT score (50-100) seems to be associated with prolonged stable disease.

Robustness of plastic scintillation microspheres in the continuous measurement of different river waters

Plastic scintillation microspheres (PSm) represent one of the most promising options for monitoring alpha and beta radioactivity in river water. For that reason, a study of the stability of PSm packed into a cell against the continuous flow of river water with different degrees of turbidity was performed over a period of 100h. The results showed that the volume of the cell became stable after 15h of pumping and continued to be stable throughout the 100h of the experiment. During this period of time, the detection efficiency of the PSm, in terms of efficiency*volume, presented mean values of 0.75(3)% for (3)H and 272(11)% for (90)Sr/(90)Y. No dependence on flow time or river water type was observed. The background was also constant for 100h and for the different water types, although (222)Rn should be removed from the water beforehand to prevent its accumulation in the PSm. Since PSm did not present any degradation throughout the whole experiment, PSm can undoubtedly be used for monitoring radioactivity with low reagent consumption, low waste generation and low maintenance costs.

Chemometrics quality assessment of wastewater treatment plant effluents using physicochemical parameters and UV absorption measurements

Chemometric techniques like Principal Component Analysis (PCA) and Partial Least Squares Regression (PLS) are used to explore, analyze and model relationships among different water quality parameters in wastewater treatment plants (WWTP). Different data sets generated by laboratory analysis and by an automatic multi-parametric monitoring system with a new designed optical device have been investigated for temporal variations on water quality parameters measured in the water influent and effluent of a WWTP over different time scales. The obtained results allowed the discovery of the more important relationships among the monitored parameters and of their cyclic dependence on time (daily, monthly and annual cycles) and on different plant management procedures. This study intended also the modeling and prediction of concentrations of several water components and parameters, especially relevant for water quality assessment, such as Dissolved Organic Matter (DOM), Total Organic Carbon (TOC) nitrate, detergent, and phenol concentrations. PLS models were built to correlate target concentrations of these constituents with UV spectra measured in samples collected at (1) laboratory conditions (in synthetic water mixtures); and at (2) WWTP conditions (in real water samples from the plant). Using synthetic water mixtures, specific wavelengths were selected with the aim to establish simple and reliable prediction models, which gave good relative predictions with errors of around 3-4% for nitrates, detergent and phenols concentrations and of around 15% for the DOM in external validation. In the case of nitrate and TOC concentrations modeling in real water samples from the effluent of the WWTP using the reduced spectral data set, results were also promising with low prediction errors (less than 20%).

[Survey national professional practice on the use of the laryngeal mask]

BACKGROUND

This survey aimed to describe the current use of laryngeal mask (LM) and to define the difference of use according to a group defined like experts.

METHODS

A self-questionnaire available on Internet was sent by e-mail to French anesthesiologists. Results were compared by a Chi(2) test between anesthesiologists according to their expertise defined by a >750 LM use.

RESULTS

Nine hundred and fifty-three anesthesiologists answered to the survey. Only 19 reported never using LM and 37% of responders were defined as expert. More than half of the MAR used the ideal weight to set the size of the MLA to use. Pressure leak was sought by less than one-third of the MAR. In case of leakage, a mobilization of the ML or the patient's head was performed first. In second intention, nearly a quarter of MAR changed technique for the benefit of oral intubation. Only 50% of responders used LM as a rescue technique in case of difficult intubation and ventilation. Experts had less insertion failure and laryngospasm. Complications and medico-legal suites are few.

CONCLUSIONS

Variability of practice may be explained by low-grade recommendations in the literature. LM insertion in case of difficult intubation/ventilation to provide adequate oxygenation and should be formally reminded to clinicians.

[Epidural analgesia apart from obstetrics: a survey of practice]

OBJECTIVES

To describe the current use of epidural anesthesia (EA) apart from obstetrics, and to explain the reasons of its low utilization.

STUDY DESIGN

Observational study.

METHODS

A survey of practice with a self-questionnaire was sent by e-mail and available on Internet. Answers were compared between groups doing or not an epidural analgesia with exact Fisher tests (P<0.05 statistically significant).

RESULTS

Among the 176 anesthesiologists who answered to the questionnaire, only 21.4% never used epidural analgesia. The main reasons were alternatives therapeutics such as PCA with opioids or TAP block (24/38 vs. 46/140). TAP block was the most common alternative used by more than 50% of anesthesiologists. Loss of competence (4/30 vs. 0/39) was rarely the reason to its low utilization. The low accessibility to specialized postoperative units was recognized in both groups as a limiting factor to do an epidural but not the fear of neurological complications. Those who never perform epidural analgesia were statistically more often physicians between 40 and 50 years (12/38 vs. 19/140). Heparin, aspirin and clopidogrel are no longer contraindications according to anesthesiologists less than 40 years old (50/68 vs. 31/68; 44/68 vs. 31/68; 37/68 vs. 23/68 respectively) but not for older.

CONCLUSIONS

Epidural analgesia is performed more often by younger anesthesiologists. This survey suggests the need of specific postoperative area to allow anesthesiologist to perform and supervise safely this technique. Recommendations of the French society of Anesthesiologists are also poorly applied.

Expression and mutational status of treatment-relevant targets and key oncogenes in 123 malignant salivary gland tumours

BACKGROUND

Malignant tumours of the salivary glands (MSGT) are rare and pleomorphic entities. Patients with advanced disease may benefit from targeted therapy; however, specific targets for optimising and personalising treatments are yet to be identified.

DESIGN

Immunohistochemistry for C-KIT, EGFR, HER2, MUC1, phospho-mTOR, androgen/estrogens/progesterone receptors and Ki67 was carried out and evaluated in terms of progression-free and overall survival. High throughput molecular screening of key oncogenes was done in 107 patients using routine diagnostic methods and Sequenom technology.

RESULTS

Several therapy leads were identified, including high levels of HER2 and androgen receptors in salivary duct carcinomas, C-KIT in myoepithelial carcinomas and EGFR in mucoepidermoid carcinomas. Recurrent mutations involving downstream elements of the EGFR pathway were found in HRAS, notably in tumours with a myoepithelial component, and in other key oncogenes (KRAS/NRAS/PI3KCA/BRAF/MAP2K). On the other hand, <1% of samples had EGFR or HER2 mutations.

CONCLUSION

Several tumour subtypes overexpressed targets of directed therapies suggesting potential therapy leads. Genotyping results suggest activation downstream of EGFR in 18 of the 107 samples that could be associated with low efficacy of EGFR inhibitors. Other molecules, such as PI3K/MEK or mTOR inhibitors, may have anti-tumour activity in this subgroup. The high mutation rate in HRAS highlights a novel key oncogenic event in MSGT.

New contributions to the ORP & DO time profile characterization to improve biological nutrient removal

Changes in the oxidation-reduction potential (ORP), pH and dissolved oxygen (DO), along with organic load and nutrient removal in a municipal wastewater treatment plant (WWTP) have been monitored throughout one year. The "nitrate knee" and the "nitrate break point" in ORP profiles, the "nitrate apex" and the "ammonia valley" in pH profiles and the "DO elbow" in DO profiles have been identified. Furthermore, these bending points have been correlated with the oxygen uptake rate (OUR), the temperature in the vessel and the aeration and non-aeration time profiles by using Principal Component Analysis (PCA). The data have been previously split up into wet and dry weather cycles by means of a K-means clustering algorithm. Finally, two new parameters have been defined: the "ORP Arrow", which is closely related to the inhibition of the denitrification process, and the "Oxygen Rise Average Slope" (ORAS), which shows the oxygen transfer rate.

[Barotrauma by Venturi effect during apnea testing for the determination of brain death. Should it change the terms of application of this test?]

The clinical diagnosis of brain death is based on three clinical criteria, one of them being the abolition of the spontaneous breathing shown by an apnoea testing [1,2]. During this manoeuvre, oxygen is administered by intratracheal way through oxygen supply tubing inserted into the endotracheal tube. Few cases of barotrauma with tension pneumothorax during this test have been described in the literature bringing to the loss of potential donor or grafts for transplantation. The authors report a new case of tension pneumothorax occurred during an apnoea testing despite the precautionary measures necessary to prevent such a catastrophic complication. In addition to the possible pathophysiologic explanation of the event advanced by the authors, it seems lawful to redefine the practical modalities of implementation of this test to avoid the loss of potential grafts.

[Anaphylactic shock to iodinated povidone]

Anaphylaxis during anaesthesia is a rare event which is mainly related to neuromuscular blocking agents. Latex and antibiotics are less frequently incriminated. However, allergy may be triggered by other less frequent and hidden allergen. Among these, povidone is largely used in numerous therapeutics and cosmetics. We report here an exceptional case of grade 3 anaphylactic shock with iodinated povidone administered via a rectal route.

Recombinant Newcastle disease virus as a vaccine vector

A complete cDNA clone of the Newcastle disease virus (NDV) vaccine strain Hitchner B1 was constructed, and infectious recombinant virus expressing an influenza virus hemagglutinin was generated by reverse genetics. The rescued virus induces a strong humoral antibody response against influenza virus and provides complete protection against a lethal dose of influenza virus challenge in mice, demonstrating the potential of recombinant NDV as a vaccine vector.

[Training research scientists for drug discovery]

National policy for pharmaceutics depends on the quality of the women and men who put it into practice. Long term investment in teaching of both research and drug development is therefore necessary. In the past our medical, pharmacology and veterinary schools have trained the directors and managers of the pharmaceutical industry. This is no longer the case today, and not only in research and development. Pharmacology schools in particular have not, on the whole, been able to incorporate the conceptual and technological requirements of contemporary pharmaceutic innovation. Profound changes in teaching 1st and 2nd cycle university courses will be necessary in order for pharmacology and medical schools to train students who will be not only competent in their specialty but also expert in drug discovery, able to play a role in the French pharmaceutical industry (and worldwide) and to become research scientists and professors who are respected by the international scientific community.

Phylogenetic analysis of chloroplast DNA variation in Coffea L

The trnL-trnF intergenic spacer of cpDNA has been sequenced from 38 tree samples representing 23 Coffea taxa and the related genus Psilanthus. These sequences were used for phylogenetic reconstruction using parsimony analyses. The results suggest a radial mode of speciation and a recent origin in Africa for the genus Coffea. Phylogenetic relationships inferred from the cpDNA analysis suggest several major clades, which present a strong geographical correspondence (i.e., west Africa, central Africa, east Africa, and Madagascar). The overall results agree well with the phylogeny previously inferred from nuclear genome data. However, several inconsistencies are observed among taxa endemic to west Africa, suggesting the occurrence of introgressive hybridization. Evidence is also obtained for the genetic origin of the allotetraploid species C. arabica.

Inheritance and restriction fragment length polymorphism of chloroplast DNA in the genus Coffea L

CpDNA variation among 52 tree samples belonging to 25 different taxa of Coffea and two species of Psilanthus was assessed by RFLP analysis on both the total chloroplast genome and the atpB-rbcL intergenic region. Twelve variable characters were distinguished allowing the identification of 12 different plastomes. The low sequence divergence observed might suggest that Coffea is a young genus. The results were in contradiction with the present classification into two genera. Additionally, cpDNA inheritance was studied in interspecific hybrids between C. arabica and C. canephora, and in an intraspecific progeny of C. canephora, using PCR-based markers. Both studies showed exclusively maternal inheritance of cpDNA.

Nuclear DNA content in the subgenus Coffea (Rubiaceae): inter- and intra-specific variation in African species

Flow cytometry has been used to estimate nuclear DNA content of 13 Coffea species (Rubiaceae) native to Africa. Twelve diploid (2n = 22) and one tetraploid (C. arabica, 2n = 44) species were investigated. Isolated nuclei from 77 genotypes were stained with propidium iodide (PI; not base specific). Thirty-nine genotypes were stained with 4′,6-diamidino-2-phenylindole (DAPI; AT specific). Nuclear DNA content (2C values), estimated with PI, ranged from 0.95 to 1.78 pg. By aggregative clustering, three groups of accessions with increasing DNA content were identified. Three species, namely C. sessiliflora, C. racemosa, and C. pseudozanguebariae, had a low DNA content (0.90 – 1.30 pg). Three species, namely C. eugenioides, C. stenophylla, and C. sp. F, were exclusively found in the intermediate group (1.31 – 1.60 pg). The remaining species were distributed between the intermediate group and the last group (1.61 – 1.80 pg). The values determined for the Coffea species are compared, inter- and intra-specifically, to those of other angiosperm species. The observed differences are discussed according to the ecogeographic origin of the species, their phenological characteristics, and the fertility of the F1 interspecific hybrids. Key words: Africa, Coffea, flow cytometry, nuclear DNA content, genome evolution.

Opioid and substance P receptor adaptations in the rat spinal cord following sub-chronic intrathecal treatment with morphine and naloxone

The effect of continuous intrathecal infusion with morphine (5 mu/h) or naloxone (2 micrograms/h) was investigated with regard to analgesia and the apparent density of mu- and delta-opioid and neurokinin-I/substance P receptors in the rat spinal cord. Morphine infusion increased tail-flick and paw-pressure responses until day 4 after the mini-osmotic pump implant. A decline in antinociception, reflecting tolerance to morphine, was then apparent in both tests. Quantitative in vitro receptor autoradiography of [125I]FK-33824, [125I][D.Ala2]deltorphin-I and [125I] Bolton-Hunter substance P binding sites, as ligands of mu, delta and neurokinin-I/substance P receptors, respectively, was performed on lumbosacral spinal cord sections of seven-days tolerant animals. Treatments with morphine and naloxone induced a similar increase (37%) in the number of delta binding sites in the superficial laminae of the dorsal horn. In contrast, the density of mu-opioid receptors was only affected by naloxone (50% increase). Neurokinin-I/substance P binding parameters were not altered by these treatments. Thus, it appears that delta-opioid binding sites may be of special relevance with regard to the development of tolerance to opiates in the spinal cord.

Effects of ibogaine on naloxone-precipitated withdrawal in morphine-dependent mice

In naive mice, ibogaine at a tremorigenic dose (30 mg/kg, ip), did not produce antinociception but did potentiate the antinociceptive potency of morphine in the tail-flick test. In morphine-dependent mice, ibogaine did not eliminate withdrawal symptoms but significantly increased the number of repetitive vertical jumps induced by naloxone, whatever the duration of the chronic morphine treatment. By comparison, repetitive jumping induced by alpha-napthoxyacetic acid (alpha-NOAA), a non-convulsant drug which induced jumping without affecting other morphine-withdrawal signs, was not significantly modified by ibogaine. These results indicate that while acute antinociceptive effects of morphine are modulated by ibogaine, this drug, shown to alleviate opiate dependence in man, does not attenuate in mice opioid withdrawal manifestations.

Further evidence that morphine-6 beta-glucuronide is a more potent opioid agonist than morphine

The antinociceptive properties of morphine-6 beta-glucuronide (M6G) and morphine (oral, i.c.v. and s.c.) were examined in two tests involving different nociceptive stimuli [i.e., cutaneous-thermal (tail-flick) and chemical-visceral (acetic acid-writhing)] in both naive and chronically treated mice. Twenty min after i.c.v. injection, M6G was 47 and 360 times more potent than morphine in the writhing and tail-flick tests, respectively. This difference was not due to differences in affinity because M6G displayed lower apparent affinities (Ki) for mu and kappa binding sites in vitro. After systemic injection, the two opiates were equieffective, although M6G produced a 10-fold longer antinociceptive effect. These differences with route of administration partially result from the hydrophilic nature of M6G because its inflow into the brain compartment was at least 10-fold lower than that of morphine, whereas the rate of elimination of the parent molecule was 3 times greater. After chronic treatment, mice readily develop tolerance and marked physical dependence to the antinociceptive effects of M6G. In vivo binding studies showed that M6G exerts its antinociceptive effect at low (less than 1%) fractional occupancy of [3H]diprenorphine-specific binding sites. In contrast, morphine needs to occupy 9.5 (writhing) to 47 (tail-flick) times more opioid binding sites to produce the same antinociceptive activity. M6G thus appears to have greater pharmacological potency than morphine, which in comparison possesses a low intrinsic efficacy.

CSF baclofen levels after intrathecal administration in severe spasticity

The pharmacokinetic parameters in the CSF of baclofen given to 4 patients as an intrathecal bolus are reported. Considerable inter-individual variability in the parameters was observed. The elimination half-life ranged from 0.9 to 5 h and the clearance from 0.013 to 0.08 l.h-1. In order to optimize treatment, it is suggested that CSF baclofen levels be matched to changes in Hoffman's monosynaptic reflex (H reflex).

High resolution radioautographic localization of [125I]FK-33-824-labelled mu opioid receptors in the spinal cord of normal and deafferented rats

Recent data have shown that [125I]D-Ala2, MePhe4, Met(o)ol5-enkephalin (FK-33-824) is a highly selective and specific mu opioid receptor ligand [Moyse et al. (1986) Peptides 7, 351-355]. This probe was used here to investigate the detailed radioautographic distribution of mu sites at various levels of the spinal cord. [125I]FK-33-824 binding sites were localized by both tritium-sensitive film and liquid emulsion radioautography in the spinal cord of naive and deafferented rats. In naive animals, high densities of mu sites were apparent within laminae I-II at all levels of the dorsal horn, with higher levels of labelling seen in layer IIi as compared to IIo in the lumbar segment. Laminae III-IV contained about half the quantities of binding observed in superficial layers. Relatively high densities of sites were also seen over lamina VI in the upper cervical cord and throughout Clarke's column. Within the latter, [125I]FK-33-824 binding clearly spared the large perikarya of the spinocerebellar neurons. In the ventral horn, [125I]FK-33-824 binding was mainly concentrated in layer IX, at the level of cervical and lumbar enlargements. Labelled sites were confined to the neuropil, mostly sparing the soma of motoneurons. Significant decreases in [125I]FK-33-824 binding in laminae I-II (55%) and III-IV (28%) were detected four days following cervical (C3-C7) or lumbar (L1-L6) rhizotomies. These decrements were most evident at seven days post-lesion at C3-C7 levels (93 and 76% in laminae I-II and III-IV, respectively) and recovered slightly thereafter up to 28 days post-lesion. In contrast, dorsal rhizotomies did not influence mu labelling in either the ventral horn or Clarke's column. These results confirm the association of mu opioid binding sites with dorsal primary afferent fibres and demonstrate the presence of mu sites in Clarke's column and lamina IX of the ventral horn. These findings suggest that endogenous opioids in the spinal cord play a role in sensory motor integration as well as in the modulation of primary nociceptive inputs.

Binding of dynorphin A and related peptides to kappa- and mu-opioid receptors: sensitivity to Na+ ions and Gpp(NH)p

We have examined the effects of Na+ ions and 5'-guanylyl imidodiphosphate (Gpp(NH)p) on the equilibrium binding of dynorphin A and of a series of related agonist and antagonist peptides to kappa- and mu-opioid receptors in guinea pig (kappa) and rabbit (mu) cerebellum membrane preparations. The binding to kappa sites of dynorphin A and of the peptides displaying agonist properties was strongly inhibited in the presence of 120 mM NaCl and 50 microM Gpp(NH)p. In contrast, a somewhat lower sensitivity to the inhibitory effect of the two allosteric effectors was observed for the analogues of the series showing antagonist properties. The same general behavior, but more marked, was observed at mu sites, at both mu- and kappa-opioid receptors. The peptides had biochemical properties (binding sensitivity vs. insensitivity to sodium ions and guanine nucleotides) that correlated well with their biological activities (agonist vs. antagonist) previously determined in in vitro pharmacological bioassays.

N,N-diallyl-tyrosyl substitution confers antagonist properties on the kappa-selective opioid peptide [D-Pro10]dynorphin A(1-11)

1. In the search for kappa-opioid antagonists, we have designed two N,N-diallyl substituted analogues of the kappa-selective peptide [D-Pro10]dynorphin A (1-11)(DPDYN). In this study, we have examined (i) the binding properties of N,N-diallyl-DPDYN (analogue 1) and N,N-diallyl-[Aib2,3]DPDYN (analogue 2) at the three main types (mu, delta, kappa) of opioid binding sites, (ii) their binding sensitivity to Na+ ions (120 mM NaCl) and guanine nucleotide (50 microM Gpp(NH)p) at mu- and kappa-binding sites and (iii) their biological activity in two pharmacological bioassays specific for mu- and kappa-(guinea-pig ileum) and kappa-(rabbit vas deferens) opioid receptors. 2. Steric hindrance resulting from incorporation of two bulky allyl groups at the tyrosal nitrogen atom greatly altered the binding properties of DPDYN. A dramatic fall in apparent affinity for the three types (mu, delta, kappa) of site as well as selectivity for kappa-sites was observed for the two N,N-diallyl-substituted peptide analogues. 3. At kappa-sites of guinea-pig cerebellum and mu-sites of rabbit cerebellum, N,N-diallyl-substitution led to a complete loss of binding sensitivity to the inhibitory effect of 120 mM NaCl + 50 microM Gpp(NH)p compared to the high sensitivity of DPDYN. This may therefore suggest that the N,N-diallyl-DPDYN analogues are endowed with opioid antagonist properties. 4. No agonist activity of the analogues was observed in guinea-pig myenteric plexus and rabbit vas deferens organ preparations. In contrast, both of the diallyl-substituted peptides displayed similar antagonist properties against the kappa-agonist DPDYN in both preparations. In the guinea-pig ileum, the affinities of the antagonist peptides against the mu-agonist Tyr-D-Ala-Gly-MePhe- NH(CH2)20H(DAGOL) were approximately half that observed against DPDYN. 5. These results show that N,N-diallyl-tyrosyl substitution leads to analogues of DPDYN which act in vitro as pure opioid antagonists and exhibit a reasonable affinity at, but a weak selectivity for, the K-opioid receptors.