Genetic factors contributing to late adverse musculoskeletal effects in childhood acute lymphoblastic leukemia survivors.

BACKGROUND: A substantial number of survivors of childhood acute lymphoblastic leukemia (ALL) suffer from treatment-related late adverse effects. While multiple studies have identified the effects of chemotherapeutics and radiation therapy on musculoskeletal outcomes, few have investigated their associations with genetic factors. METHODS: Here we analyzed musculoskeletal complications in relation to common and rare genetic variants derived through whole-exome sequencing of the PETALE cohort. Top-ranking associations were further assessed through stratified and multivariate analyses. RESULTS: DUOX2 variant was associated with skeletal muscle function deficit, as defined by peak muscle power Z score ≤ -2 SD (P = 4.5 × 10-5 for genotyping model). Upon risk stratification analysis, common variants in the APOL3, COL12A1, and LY75 genes were associated with Z score ≤ -2 SD at the cross-sectional area (CSA) at 4% radial length and lumbar bone mineral density (BMD) in high-risk patients (P ≤ 0.01). The modulation of the effect by risk group was driven by the interaction of the genotype with cumulative glucocorticoid dose. Identified variants remained significant throughout multivariate analyses incorporating non-genetic factors of the studied cohort. CONCLUSION: This exploratory study identified novel genetic variants associated with long-term musculoskeletal impairments in childhood ALL survivors. Replication in an independent cohort is needed to confirm the association found in this study.

[Procedure for daylight methyl aminolevulinate photodynamic therapy to treat actinic keratoses]. / Modalités pratiques de traitement des kératoses actiniques par photothérapie dynamique topique en lumière du jour avec l'aminolévulinate de méthyle.

Actinic keratosis (AK), also known as solar keratosis or pre-cancerous keratosis, is frequently observed in areas of skin exposed to sunlight, particularly in light-skinned patients. In France, photodynamic therapy using red light (conventional PDT) and methylamino 5-levulinate (MAL) is indicated in the treatment of thin or non-hyperkeratotic and non-pigmented multiple AK lesions or large zones covered with AK lesions. It is well-known for its efficacy but also for its side effects, especially pain during illumination, which can limit its use. An alternative to PDT using natural daylight has recently been proposed to treat actinic keratosis lesions, and results in greater flexibility as well as significant reduction in pain. The lesions are prepared as for conventional PDT, with MAL cream being applied by the physician or the patient, after which they are exposed to natural daylight for 2hours. The lesions are then gently cleansed and protected from natural light for 24hours. This paper seeks to provide a precise description of the daylight PDT procedure for the treatment of AK.

Development and psychometric validation of the REFlective evaLuation of psoriasis Efficacy of Treatment and Severity (REFLETS) questionnaire: a common measure of plaque-type psoriasis severity and treatment efficacy for patients and clinicians.

BACKGROUND: To date, there is no global consensus on the definition of the severity of psoriasis. The REFlective evaLuation of psoriasis Efficacy of Treatment and Severity (REFLETS) questionnaire has recently been developed to provide a better understanding of plaque-type psoriasis severity and treatment efficacy from both patient and clinician perspectives. OBJECTIVE: This study aimed to develop and psychometrically validate the new REFLETS questionnaire to evaluate patient and clinician perceptions of plaque-type psoriasis severity and treatment efficacy. METHODS: Two similar versions of the REFLETS questionnaire were developed following a rigorous methodology for clinicians and patients, referring to 'the psoriasis of your patient' or to 'your psoriasis', respectively. An observational, longitudinal, multicentre study was conducted in France with 34 dermatologists and 430 mild to severe plaque-type psoriasis patients to finalize the questionnaire and evaluate its psychometric properties. RESULTS: Two dimensions were defined--severity and treatment efficacy--with three subdimensions within severity (impact of psoriasis, symptoms and disease course), and two individual items on joint pain. The questionnaire was well accepted by clinicians and patients. Excellent internal consistency (Cronbach's alpha = 0.66-0.98) and test-retest reliability (intraclass correlation coefficients = 0.83-0.94) were demonstrated. REFLETS scores were moderately to highly correlated to Psoriasis Area and Severity Index (r = 0.35-0.70), Skindex-29 (r = 0.46-0.82) and DLQI scores (r = 0.36-0.82). Patients with decreased psoriasis severity and those with increased treatment efficacy, according to patient global evaluations, had lower severity and higher treatment efficacy REFLETS scores, respectively. CONCLUSION: REFlective evaLuation of psoriasis Efficacy of Treatment and Severity is a promising tool for assessing plaque-type psoriasis severity and treatment efficacy from patient and clinician perspectives. It may help to improve patient and clinician communication in treatment decision making.

French teenagers and artificial tanning.

BACKGROUND: Exposure to solar and artificial ultraviolet (UV) radiations is a major risk factor for skin cancers. France has enacted one of the strictest laws that, notably, restrict tanning-bed access to adults ≥18 years old. OBJECTIVE: We evaluated artificial tanning behaviours of French teenagers (11-17 years old): sunless-tanning products, sunlamps and artificial tanning beds. METHODS: An anonymous questionnaire evaluating sunburn history, skin phototype, behaviours with sunless-tanning products and indoor tanning, and parents' behaviours was distributed to students enrolled in two middle and high schools in Antony, a typical city of the middle class French population, located in the Paris suburbs. RESULTS Among 713 teenagers (mean age: 13.5 years: male/female: 1.1) responding, more than half declared that it was important to be tanned during the summer, 1% reported having already used tanning pills, 9.9% tanning creams and 1.4% indoor tanning. Female teenagers significantly more frequently resorted to indoor tanning (P = 0.02), cited the importance of being tanned all year long (P < 0.0001), used tanning pills (P < 0.0001) or tanning creams (P < 0.006), and their parents relied on indoor tanning (P < 0.0001). Profiles of tanning-pill and -cream users were similar. Mean ages for the two groups were comparable. CONCLUSION: French regulations for indoor tanning seem quite effective. Our analyses revealed a typical teenager profile with sun-exposure risk behaviours, for example, indoor tanning, and use of tanning pills or creams. They could be a selective target for sun-protection information campaigns.

[Socio-demographic study of privately practicing dermatologists in metropolitan France in 2011]. / Étude sociodémographique des dermatologues libéraux en France métropolitaine en 2011.

BACKGROUND: There is currently an alarming decrease in the number of dermatologists in private practice because of the limited number of new graduates, who are unable to compensate for departures into retirement among the "baby boom" generation. Our aim was thus to determine the socio-demographic characteristics of private dermatologists in France in 2011 to forecast the impact over the next 20 years. MATERIALS AND METHODS: Analysis was performed of socio-demographic data (age, sex, place of practice, thesis year and mode of exercise) for all private dermatologists living in France in 2011 and identified in the Rosenwald Directory of Doctors. These data were combined with those of the National Council of the Order to determine the number of GPs and those of INSEE, giving the size and number of inhabitants of each department. RESULTS: There are 3,197 privately practicing dermatologists in France, with a majority of women (65%). The average age is 52 years. Fifty-three per cent of dermatologists are aged over 55 years while 21% are aged between 50 and 54 years, 19% are aged between 40 and 49 and 5% are aged under 39 years. The density of dermatologists in France is 5.1/100,000 inhabitants. There are three types of density zone for dermatologists: high-density zones (over five dermatologists per 10(5) persons), comprising 24 departments (22% of the national territory) in which 61% of dermatologists are practicing; moderate-density zones (three to five dermatologists per 10(5) persons), comprising 41 departments (47% of the French territory in which 30% of dermatologists are practicing; low-density zones (less than three dermatologists per 10(5) persons), considered as "dermatological deserts", comprising 30 departments (31% the national territory) in which 10% of the country's dermatologists are practicing. The population projection shows a decrease in the number of dermatologists in private practice of 45% in 2020, 72% in 2025 and 84% in 2030. DISCUSSION: Our study highlights the disparity in distribution of the density of liberal dermatologists in France. The departments in which the density of dermatologists is low are those where the number of general practitioners is small. In 2021, 54% of dermatologists currently in private practice will be aged over 65 and are therefore likely to end their professional practice. How can we anticipate the fall in the number of dermatologists in private practice over the coming two decades? This question must be addressed urgently.

The antinociceptive effects of intraplantar injections of 2-arachidonoyl glycerol are mediated by cannabinoid CB2 receptors.

BACKGROUND AND PURPOSE: 2-arachidonoyl glycerol (2-AG) is an endogenous cannabinoid with central antinociceptive properties. Its degradation is catalysed by monoacylglycerol lipase (MGL) whose activity is inhibited by URB602, a new synthetic compound. The peripheral antinociceptive effects of 2-AG and URB602 in an inflammatory model of pain are not yet determined. We have evaluated these effects with and without the cannabinoid CB(1) (AM251) and CB(2) (AM630) receptor antagonists. EXPERIMENTAL APPROACH: Inflammation was induced in rat hind paws by intraplantar injection of formalin. Nociception was assessed behaviourally over the next 60 min, in 19 experimental groups: (1) control; (2-6) 2-AG (0.01-100 microg); (7) AM251 (80 microg); (8) AM251+2-AG (10 microg); (9) AM630 (25 microg); (10) AM630+2-AG (10 microg); (11-16) URB602 (0.1-500 microg); (17) 2-AG+URB602 (ED(50)); (18) AM251+URB602 (ED(50)); (19) AM630+URB602 (ED(50)). Drugs were injected s.c. in the dorsal surface of the hind paw (50 microl), 15 min before formalin injection into the same paw. KEY RESULTS: 2-AG and URB602 produced dose-dependent antinociceptive effects for the late phases of the formalin test with ED(50) of 0.65+/-0.455 mug and 68+/-14.3 microg, respectively. Their combination at ED(50) doses produced an additive antinociceptive effect. These effects were inhibited by AM630 but not by AM251 for 2-AG and by the two cannabinoid antagonists for URB602. CONCLUSIONS AND IMPLICATIONS: Locally injected 2-AG and URB602 decreased pain behaviour in a dose-dependent manner in an inflammatory model of pain. The antinociceptive effect of 2-AG was mediated by the CB(2) receptor.

Crystal structures of HIV-2 protease in complex with inhibitors containing the hydroxyethylamine dipeptide isostere.

BACKGROUND: The HIV protease is essential for the life cycle of the virus and is an important target for the development of therapeutic treatments against AIDS. The structures of HIV protease in complex with different inhibitors have helped in understanding the interactions between inhibitors and the protease and in the design and optimization of HIV protease inhibitors. RESULTS: We report here crystal structures at up to 1.7 A resolution of the homodimeric HIV-2 protease in complex with seven inhibitors containing the hydroxyethylamine dipeptide isostere. A novel dimethylphenoxyacetyl group that is present in some of these inhibitors is inserted between residues 48' and 49' in the flap of the protease and residues 29' and 30' (where a prime indicates a residue in the second monomer), which undergo a conformational change to accommodate the phenyl ring of the inhibitor. CONCLUSIONS: This study shows that besides the residues in the flap and residues 79-81 in the S1 substrate-binding pocket which undergo conformational changes upon inhibitor binding, residues 29 and 30 can also adapt their conformation to fit certain inhibitors. Conformational flexibility of the HIV protease plays an important role in inhibitor binding.

In vivo detection of reperfused myocardium by nuclear magnetic resonance imaging.

To assess the potential of in vivo nuclear magnetic resonance imaging for the detection of reperfused myocardium, in vivo T2-weighted spin echo images were obtained of dogs at 0.15 tesla. Imaging was done during 3 hours of coronary occlusion (group I), and during 3 hours of coronary occlusion followed by 1 hour of reperfusion (group II). On sacrifice, the hearts were drained of blood and imaged in situ to determine the effect of in vivo imaging on myocardial signal intensity. The hearts were then excised and imaged at 1.4 tesla to compare the effect of high resolution imaging on image quality. Of the six hearts in group I and the eight hearts in group II with a myocardial infarction and suitable image quality, four of the former hearts and six of the latter demonstrated a small but visible increase in infarct signal intensity at 3 hours of occlusion on the time to echo [TE] = 60 ms, single echo images. The T2 (transverse) relaxation time of the infarct (measured in vitro by spectrometer) increased by 13% when compared with normal tissue. In contrast, the reperfused infarct was more easily visualized, with signal intensity increasing by 31 +/- 17% and infarct T2 increasing by 20%. Imaged at 1.4 tesla, the excised hearts showed the infarct to be subendocardial during occlusion and extending transmurally with reperfusion. It is concluded that, although visualized, the increase in infarct signal intensity at 3 hours of coronary occlusion is small and this is consistent with the small increase in infarct signal intensity and T2 relaxation.(ABSTRACT TRUNCATED AT 250 WORDS)

Behavioral, pharmacological and molecular characterization of the saphenous nerve partial ligation: a new model of neuropathic pain.

The saphenous partial ligation (SPL) model is a new, easily performed, rodent model of neuropathic pain that consists of a unilateral partial injury to the saphenous nerve. The present study describes behavioral, pharmacological and molecular properties of this model. Starting between 3 and 5 days after surgery, depending on the modality tested, animals developed clear behaviors indicative of neuropathic pain such as cold and mechanical allodynia, and thermal and mechanical hyperalgesia compared with naive and sham animals. These pain behaviors were still present at 1 month. Signs of allodynia also extended to the sciatic nerve territory. No evidence of autotomy or bodyweight loss was observed. Cold and mechanical allodynia but not thermal and mechanical hyperalgesia was reversed by morphine (4 mg/kg i.p.). The cannabinoid receptor agonist WIN 55,212-2 (5 mg/kg i.p.) improved signs of allodynia and hyperalgesia tested except for mechanical hyperalgesia. Gabapentin (50 mg/kg i.p.) was effective against cold and mechanical allodynia but not hyperalgesia. Finally, amitriptyline (10 mg/kg i.p.) failed to reverse allodynia and hyperalgesia and its administration even led to hyperesthesia. Neurobiological studies looking at the expression of mu opioid receptor (MOR), cannabinoid CB(1) and CB(2) receptors showed a significant increase for all three receptors in ipsilateral paw skin, L3-L4 dorsal root ganglia and spinal cord of neuropathic rats compared with naive and sham animals. These changes in MOR, CB(1) and CB(2) receptor expression are compatible with what is observed in other neuropathic pain models and may explain the analgesia produced by morphine and WIN 55,212-2 administrations. In conclusion, we have shown that the SPL is an adequate model that will provide a new tool for clarifying peripheral mechanisms of neuropathic pain in an exclusive sensory nerve.

Peptidic regulation of heart rate and interactions with the autonomic nervous system.

Autonomic influences on the heart rate have been the subject of intense research for many decades and are classically devoted to the sympathetic and parasympathetic systems. However, developments over the past few years in our knowledge of the organization of the autonomic nervous system have led to the conclusion that in addition to the classical transmitters, peptidic transmitters are clearly present and have direct or indirect actions on cardiac conduction. Neuropeptides have been found to collocate with each other or with classical transmitters, thereby increasing the variety of chemical signals that a neuron can utilize to communicate with other cells. Neuropeptides can act as neurotransmitters, neuromodulators or neurohormones. Some are produced in endocrine glands and circulate as hormones, while others are contained in cardiac myocytes, neurons, or endothelial cells in proximity to the sinoatrial node and can therefore act in a paracrine or autocrine way on the pacemaker cells to modulate heart frequency. There is evidence supporting such a role, especially for locally situated neuropeptide Y, vasoactive intestinal peptide, calcitonin gene-related peptide, substance P, angiotensin II, natriuretic peptides, endothelins and possibly many others. The role of the peptidic neurotransmitters in the conduction system should not be exaggerated. Nevertheless, neuropeptides certainly represent a new category of neurotransmitters forming a third component of the autonomic nervous system and may have complex actions with potential therapeutic implications in man.

Analgesic interaction between ondansetron and acetaminophen after tonsillectomy in children: the Paratron randomized, controlled trial.

BACKGROUND: The mechanism of action of acetaminophen remains unclear. One hypothesis involves an interaction with the serotoninergic system. Antagonists to serotonin (5-HT)3 receptors (setrons) have antiemetic properties. Therefore, co-administration of acetaminophen and a setron could lead to a decrease or a loss of acetaminophen analgesic effects. The aim of this study was to demonstrate such an interaction. METHODS: Paratron is a prospective, randomized, controlled, double-blind, parallel group trial. All children aged 2-7 years (n = 69) scheduled for a tonsillectomy ± adenoidectomy received intraoperative acetaminophen with ondansetron or droperidol. Pain scores [Children's Hospital of Eastern Ontario Pain Scale (CHEOPS)], morphine consumption and the incidence of post-operative nausea and vomiting (PONV) were measured for 24 h following surgery. RESULTS: Pain scores were not different at all times between the groups but median morphine consumption (µg) in recovery was 322.5 [interquartile range (IQR) 0.0-500.0] and 0 (IQR 0-0) in the ondansetron (n = 35) and droperidol (n = 34) groups, respectively (p = 0.004). The percentages of patients who received morphine titration were 57.1% and 20.6% in the ondansetron and droperidol groups, respectively (p = 0.008). No significant difference was found for PONV. CONCLUSIONS: An interaction between acetaminophen and ondansetron is suggested, with children receiving three times more morphine during pain titration in the recovery room. More studies are necessary to evaluate whether this finding is clinically relevant enough to preclude the simultaneous perioperative administration of both drugs in the future.

Peptidomimetic inhibitors of herpes simplex virus ribonucleotide reductase: a new class of antiviral agents.

We have been investigating a new class of antiviral compounds effective against herpes simplex virus (HSV) in vitro and in vivo. Antiviral activity results from inhibition of HSV ribonucleotide reductase (RR). The inhibitors are designed as mimics of the RR small subunit C-terminus, a region essential for RR subunit association and consequently enzymatic activity. Inhibition results from specific binding of the inhibitor to the HSV RR large subunit thereby preventing subunit association. This report details the structure--activity studies that lead to the indentification of BILD 1263, a potent inhibitor of HSV RR subunit association (IC50, 0.2 nM) that also inhibits the replication of HSV types 1 and 2 in cell culture (EC50, 3 and 4 microM) and reduces the severity of HSV-1-induced keratitis in a murine ocular model. The discovery of inhibitors with in vitro antiviral results from a combination of improving inhibitor potency in a RR binding assay and modifying inhibitor physicochemical properties. The importance and possible role of the new structural modifications introduced into this inhibitor series is discussed.

Inhibition of herpes simplex virus type 1 ribonucleotide reductase by substituted tetrapeptide derivatives.

It is known that peptides corresponding to the C-terminus of the small subunit of herpes simplex virus type 1 and 2 ribonucleotide reductase can inhibit enzymatic activity by preventing the association of the enzyme's two subunits. In a quest for smaller, more potent inhibitors, we have conducted a structure activity investigation based on the pentapeptide H-Val-Val-Asn-Asp-Leu-OH. Potency increases of up to 4000 times (IC50 0.18 microM) have been achieved in an enzymatic assay by a combination of modifying the N-terminal valine to a diethylacetyl group, adding a methyl group to the beta-carbon of the adjacent valine, dialkylating the asparagine side-chain nitrogen and dimethylating the beta-carbon of the aspartic acid residue. In addition the relative contribution of various inhibitor functionalities to inhibitor potency has been investigated.

Potent HIV protease inhibitors containing a novel (hydroxyethyl)amide isostere.

A series of HIV protease inhibitors containing a novel (hydroxyethyl)amidosuccinoyl core has been synthesized. These peptidomimetic structures inhibit viral protease activity at low nanomolar concentrations (IC50 < 10 nM for HIV-1 protease). The inhibition constant (Ki) for inhibitor 19 was determined to be 7.5 pM against HIV-1 and 1.2 nM against HIV-2 proteases, respectively. Several compounds (19-24) inhibited HIV-1 replication in cell culture assays with 50% effective concentrations (EC50) = 3.7-35 nM. This series of inhibitors was found to exhibit poor bioavailability (< 10%) in the rat, following oral administration. The synthesis and biological properties of these compounds are discussed. In addition, an X-ray structure of one of these inhibitors (23) in complex with HIV-2 protease provides insight into the binding mode of this novel class of HIV protease inhibitors.

Ureido-based peptidomimetic inhibitor of herpes simplex virus ribonucleotide reductase: an investigation of inhibitor bioactive conformation.

We have been investigating peptidomimetic inhibitors of herpes simplex virus (HSV) ribonucleotide reductase (RR). These inhibitors bind to the HSV RR large subunit and consequently prevent subunit association and subsequent enzymatic activity. This report introduces a new series of compounds that contain an extra nitrogen (a ureido function) at the inhibitor N-terminus. This nitrogen improves inhibitor binding potency 50-fold over our first published inhibitor series. Evidence supports that this improvement in potency results from a new hydrogen-bonding contact between the inhibitor and the RR large subunit. This report also provides evidence for the bioactive conformation around two important amino acid residues contained in our inhibitors. A tert-butyl group, which contributes 100-fold to inhibitor potency but does not directly bind to the large subunit, favors an extended beta-strand conformation that is prevalent in solution and in the bound state. More significantly, the bioactive conformation around a pyrrolidine-modified asparagine residue, which contributes over 30 000-fold to inhibitor potency, is elucidated through a series of conformationally restricted analogues.

Peptidomimetic inhibitors of herpes simplex virus ribonucleotide reductase with improved in vivo antiviral activity.

We have been investigating the potential of a new class of antiviral compounds. These peptidomimetic derivatives prevent association of the two subunits of herpes simplex virus (HSV) ribonucleotide reductase (RR), an enzyme necessary for efficient replication of viral DNA. The compounds disclosed in this paper build on our previously published work. Structure-activity studies reveal beneficial modifications that result in improved antiviral potency in cell culture in a murine ocular model of HSV-induced keratitis. These modifications include a stereochemically defined (2,6-dimethylcyclohexyl)amino N-terminus, two ketomethylene amide bond isosteres, and a (1-ethylneopentyl)amino C-terminus. These three modifications led to the preparation of BILD 1351, our most potent antiherpetic agent containing a ureido N-terminus. Incorporation of the C-terminal modification into our inhibitor series based on a (phenylpropionyl)valine N-terminus provided BILD 1357, a significantly more potent antiviral compound than our previously published best compound, BILD 1263.

2',6'-Dimethylphenoxyacetyl: a new achiral high affinity P(3)-P(2) ligand for peptidomimetic-based HIV protease inhibitors.

Starting from palinavir (1), our lead HIV protease inhibitor, we have discovered a new series of truncated analogues in which the P(3)-P(2) quinaldic-valine portion of 1 was replaced by 2', 6'-dimethylphenoxyacetyl. With EC(50)'s in the 1-2 nM range, some of these compounds are among the most potent inhibitors of HIV replication in vitro, reported to date. One of the most promising members in this series (compound 27, BILA 2185 BS) exhibited a favorable overall pharmacokinetic profile, with 61% apparent oral bioavailability in rat. X-ray crystal structures and molecular modeling were used to rationalize the high potency resulting from incorporation of this structurally simple, achiral ligand into the P(3)-P(2) position of hydroxyethylamine-based HIV protease inhibitors.

Phosphotyrosine-containing dipeptides as high-affinity ligands for the p56lck SH2 domain.

Src homology-2 (SH2) domains are noncatalytic motifs containing approximately 100 amino acid residues that are involved in intracellular signal transduction. The phosphotyrosine-containing tetrapeptide Ac-pYEEI binds to the SH2 domain of p56lck (Lck) with an affinity of 0.1 microM. Starting from Ac-pYEEI, we have designed potent antagonists of the Lck SH2 domain which are reduced in peptidic character and in which the three carboxyl groups have been eliminated. The two C-terminal amino acids (EI) have been replaced by benzylamine derivatives and the pY + 1 glutamic acid has been substituted with leucine. The best C-terminal fragment identified, (S)-1-(4-isopropylphenyl)ethylamine, binds to the Lck SH2 domain better than the C-terminal dipeptide EI. Molecular modeling suggests that the substituents at the 4-position of the phenyl ring occupy the pY + 3 lipophilic pocket in the SH2 domain originally occupied by the isoleucine side chain. This new series of phosphotyrosine-containing dipeptides binds to the Lck SH2 domain with potencies comparable to that of tetrapeptide 1.

Nonpeptidic, monocharged, cell permeable ligands for the p56lck SH2 domain.

p56lck is a member of the src family of tyrosine kinases and plays a critical role in the signal transduction events that lead to T cell activation. Ligands for the p56lck SH2 domain have the potential to disrupt the interaction of p56lck with its substrates and derail the signaling cascade that leads to the production of cytokines such as interleukin-2. Starting from the quintuply charged (at physiological pH) phosphorylated tetrapeptide, AcpYEEI, we recently disclosed (J. Med. Chem. 1999, 42, 722 and J. Med. Chem. 1999, 42, 1757) the design of the modified dipeptide 3, which carries just two charges at physiological pH. Here we present the elaboration of 3 to the nonpeptidic, monocharged compound, 9S. This molecule displays good binding affinity for the p56lck SH2 domain (K(d) 1 microM) and good cell permeation, and this combination of properties allowed us to demonstrate clear-cut inhibitory effects on a very early event in T cell activation, namely calcium mobilization.