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BackgroundFoot compartment syndrome (FCS) has been reported to cause neuropathic pain, claw or hammer toes, and motor and sensory disturbances. The optimal treatment of FCS is controversial. The purpose of this study was to determine if foot fasciotomies improve patient outcomes in high-energy, combat-related lower extremity trauma.MethodsMedical records of patients with documented FCS from May 2007 to January 2009 were retrospectively reviewed. Consecutive, matched control patients were identified based on similar hindfoot, mid-foot and/or forefoot injuries who did not undergo foot fasciotomy during the same period. The primary outcomes analysed were the development of claw or hammer toes and neuropathic pain.Results19 patients with foot fasctiotomies were identified and matched with 19 controls. Median follow-up was 19.5 months (range, 3.5–47.5 months) for the combined cohorts. The most common mechanism of injury was an explosive blast. Nine fasciotomy and nine control patients sustained open foot fractures. Significantly more patients with foot fasciotomies developed claw toes (50% vs 17%, p=0.03). There were no significant differences in the development of neuropathic pain, sensory deficits, motor deficits, chronic pain, stiffness or infection. The fasciotomy patients underwent an average of 5.5 surgeries per patient versus 4 surgeries per patient in the control group.ConclusionsFasciotomy of the foot did not prevent neuropathic pain and deformities in patients with FCS in this study.

Proton pump inhibitor (PPI) antacid drugs have been shown to reduce the risk of gastrointestinal bleeding in patients taking antithrombotic medications and have been recommended for high risk patients since the publication of the 2008 ACCF/ACG/AHA consensus recommendations. We aimed to evaluate the rate of PPI use among outpatients receiving antithrombotic therapy at our tertiary care center.

Recent reports have documented the rate of heterotopic ossification (HO) formation in the residual limbs of combat-related amputees from the US Armed Forces injured in Operations Iraqi and Enduring Freedom. Final amputation level within the zone of injury and blast as the mechanism of injury were identified as possible risk factors for the occurrence and grade of HO. There has been no previous description of HO in combat-related amputees from the UK service personnel. The purpose of this study was to examine potential differences in the prevalence of HO between UK and US Allied Forces, with particular attention to these risk factors, patient exposures, and any treatment differences between these two groups.

17β-Hydroxysteroid dehydrogenases (17β-HSDs) are an important class of steroidogenic enzymes that regulate the bioavailability of active estrogens and androgens and are as yet a relatively unexploited therapeutic target. Based on our investigations and those of others, E-ring modified steroids were identified as a useful template for the design of inhibitors of 17β-HSD type 1, an enzyme involved in the conversion of estrone into estradiol. The synthesis and biological evaluation of a new series of N- and C-substituted 1,3,5(10)-estratrien-[17,16-c]-pyrazoles and the corresponding SAR are discussed. Among the N-alkylated analogues, the most potent inhibitor was the 1‘-methoxyethyl derivative, 41, with an IC50 of 530 nM in T47-D human breast cancer cells. The X-ray crystal structure of the 1‘-isobutyl derivative, 37, was determined. Further optimization of the template using parallel synthesis resulted in a library of C5‘-linked amides from which 73 emerged. This pyridylethyl amide had an IC50 of 300 nM and its activity, with that of 41, suggests the importance of hydrogen bond acceptor groups in the pyrazole side chain. Both 41 and 73 displayed selectivity over 17β-HSD type 2, and preliminary investigations showed 41 to be nonestrogenic in vitro in a luciferase reporter gene assay in contrast to the parent pyrazole 25. Molecular modeling studies, which support these findings, and a QSAR, the predictive power of which was demonstrated, are also presented.

Efficient and flexible syntheses of 2-substituted estrone, estradiol and their 3-O-sulfamate (EMATE) derivatives have been developed using directed ortho-lithiation methodology. 2-Substituted EMATEs display a similar antiproliferative activity profile to the corresponding estradiols against a range of human cancer cell lines. 2-Methoxy (3, 4), 2-methylsulfanyl (20, 21) and 2-ethyl EMATEs (32, 33) proved the most active compounds with 2-ethylestradiol-3-O-sulfamate (33), displaying a mean activity over the NCI 55 cell line panel 80-fold greater than the established anticancer agent 2-methoxyestradiol (2). 2-Ethylestradiol-3-O-sulfamate (33) was also an effective inhibitor of angiogenesis using three in vitro markers, and various 2-substituted EMATEs also proved to be inhibitors of steroid sulfatase (STS), a therapeutic target for the treatment of hormone-dependent breast cancer. The potential of this novel class of multimechanism anticancer agents was confirmed in vivo with good activity observed in the NCI hollow fiber assay and in a MDA-MB-435 xenograft mouse model.

Structure-based drug design using the crystal structure of human 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) led to the discovery of novel, selective, and the most potent inhibitors of 17β-HSD1 reported to date. Compounds 1 and 2 contain a side chain with an m-pyridylmethyl-amide functionality extended from the 16β position of a steroid scaffold. A mode of binding is proposed for these inhibitors, and 2 is a steroid-based 17β-HSD1 inhibitor with the potential for further development.

The design and synthesis of dimeric versions of the intracellular signaling molecule d-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] are reported. Ins(1,4,5)P3 dimers in a range of sizes were constructed by conjugation of a partially protected 2-O-(2-aminoethyl)-Ins(1,4,5)P3 intermediate with activated oligo- and poly(ethylene glycol) (PEG) tethers, to give benzyl-protected dimers with amide or carbamate linkages. After deprotection, the resulting water-soluble Ins(1,4,5)P3 dimers were purified by ion-exchange chromatography. The interaction of the Ins(1,4,5)P3 dimers with tetrameric Ins(1,4,5)P3 receptors was explored, using equilibrium [³H]Ins(1,4,5)P3-binding to membranes from cerebellum, and ⁴⁵Ca²⁺-release from permeabilized hepatocytes. The results showed that dimers, even when they incorporate large PEG tethers, interact potently with Ins(1,4,5)P3 receptors, and that the shorter dimers are more potent than Ins(1,4,5)P3 itself. A very small dimer, consisting of two Ins(1,4,5)P3 motifs joined by a short N,N‘-diethylurea spacer, was synthesized. Preliminary studies of ⁴⁵Ca²⁺ release from the intracellular stores of permeabilized hepatocytes showed this shortest dimer to be almost as potent as adenophostin A, the most potent Ins(1,4,5)P3 receptor ligand known. Possible interpretations of this result are considered in relation to the recently disclosed X-ray crystal structure of the type 1 Ins(1,4,5)P3 receptor core binding domain.

The synthesis of a series of adenophostin A analogues modified at C-6 and C-2 of adenine is described. The target compounds were synthesized by a convergent route involving a modified Vorbrüggen condensation of either 6-chloropurine or 2,6-dichloropurine with a protected disaccharide, yielding two versatile intermediates capable of undergoing substitution with a range of nucleophiles. The new analogues showed a range of abilities to mobilize Ca²⁺ from the intracellular stores of permeabilized hepatocytes and are among the first totally synthetic compounds to approach the activity of adenophostin A. In agreement with the biological results, docking studies of adenophostin A using the recently reported X-ray crystal structure of the type 1 Ins(1,4,5)P3 receptor binding core suggested that, in likely binding modes of adenophostin A, the area around N⁶ may be relatively open, identifying this region of the adenophostin A molecule as a promising target for further elaboration. The docking results also point to specific interactions involving residues within the binding domain of the Ins(1,4,5)P3 receptor that may be involved in the molecular recognition of the adenophostins.

Cyclic ADP-carbocyclic-ribose (cADPcR, 2) is a biologically and chemically stable equivalent of cyclic ADP-ribose (cADPR, 1), a Ca²⁺-mobilizing second messenger. In this study, a series of 8-substituted analogues of cADPcR, namely the 8-chloro analogue 6 (8-Cl-cADPcR), the 8-azido analogue 7 (8-N3-cADPcR), the 8-amino analogue 8 (8-NH2-cADPcR), and the 8-phenylthio analogue 9 (8-SPh-cADPcR), were designed as effective pharmacological tools for studies on cADPR-modulated Ca²⁺ signaling pathways. These target compounds were synthesized by a convergent route via 8-Cl-cADPcR bisacetonide (14) as the common intermediate, in which a method for forming the intramolecular pyrophosphate linkage by activation of the phenylthiophosphate type substrate 15 with AgNO3 to produce 14 was used as the key step. The carbocyclic analogues were tested for activity in the sea urchin egg homogenate system. Compounds were assessed for their calcium-mobilizing effects and their ability to cross-desensitize with calcium release induced by a normally maximal concentration of cADPR, as well as cADPR antagonism of cADPR-evoked calcium release. While cADPcR was 3−4 times more potent than cADPR, the 8-substituted analogues were less efficacious, with 8-SPh-cADPcR largely acting as a competitive antagonist. Most surprisingly, given that 8-N3-cADPR and 8-NH2-cADPR are known as potent antagonists, 8-N3-cADPcR and 8-NH2-cADPcR were full agonists, but ca. 80 and 2 times less potent than cADPR, respectively. These data contribute to developing structure−activity relationships for the interaction of cADPR with its receptor.

Aromatase inhibitors in clinical use block the biosynthesis of estrogens. Hydrolysis of estrone 3-sulfate by steroid sulfatase is an important additional source of tumor estrogen, and blockade of both enzymes should provide a more effective endocrine therapy. Sulfamoylated derivatives of the aromatase inhibitor YM511 inhibited sulfatase and aromatase in JEG-3 cells with respective IC50 values of 20−227 and 0.82−100 nM (cf. letrozole, 0.89 nM). One dual inhibitor was potent against both enzymes in vivo, validating the concept.

The crystal and molecular structure of the antimalarial compound artesunate has been determined by direct methods. Crystals are orthorhombic, P212121, a= 9.8371(12), b= 10.517(2), c= 18.7594(5) Å, Z= 4, Dc= 1.316 mg/mL. The molecule is comprised of a fused ring system containing a six-membered ring C which includes an oxygen bridge and a peroxy bridge. The 9-atom oxygen–carbon chain from O(5)—C(12)... to ... O(2)—C(6) displays a striking sequence of short, long, short, long ... bonds while these distances are all within the ranges of a normal single bond or partial double bond. It is proposed that this pattern is caused by the delocalization of the lone pair electrons on the oxygen atoms. The ring C has a distorted boat conformation and the C—O—O—C torsion angle is 46.3(2)°. Rings A and D have ideal chair conformations. Ring junctions A/B and A/D are cis junctions, B/D and C/D are trans. Packing of the molecules is stabilized by one strong hydrogen bond involving the hydroxyl group on the ester linkage and the oxygen atom of the lactone ring.

The crystal and molecular structure of the nematogenic compound 4(1″-butenyl) 4′(cyano)1,1′ bicyclohexane, C 17 H 27 N, has been determined from X-ray diffraction analysis at 273 K. The compound crystallizes in the form of a centrosymmetric monoclinic system with space group P2 1 /c, a=6.4040 (1) Å, b=20.4180(l) Å, c=22.9570(1) Å, β=94.9570(l)°, and z=8. Two independent molecules in the crystal have slightly different conformations, but the geometric parameters are normal. The molecular packing is nematic-like.

The synthesis of a novel and potent Ins(3,4,5,6)P4 1-kinase/Ins(1,3,4)P3 5/6 kinase inhibitor and its enantiomer is described. d-chiro-Inositol 2,3,4,5-tetrakisphosphate [d-chiro-Ins(2,3,4,5)P4, 3, Figure 1] and l-chiro-inositol 2,3,4,5-tetrakisphosphate [l-chiro-Ins(2,3,4,5)P4, ent-3] were synthesized from d-1,6-di-O-benzyl-chiro-inositol and l-1,6-di-O-benzyl-chiro-inositol, respectively. We examined inhibition of the multifunctional Ins(3,4,5,6)P4 1-kinase/Ins(1,3,4)P3 5/6-kinase from bovine aorta by 3 and ent-3. Compound 3 was a potent inhibitor with an IC50 of 1.5 μM, and ent-3 was more than 20-fold less active. The results are compared to those for other inhibitory inositol polyphosphates with structure−activity relationship discussion. Compound 3 is a useful lead for development of further inhibitors of this important enzyme, and ent-3 should find applications in the newly emerging Ins(1,4,5,6)P4 signaling pathway.

The high affinity of adenophostin A for 1d-myo-inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] receptors may be related to an alteration in the position of its 2‘-phosphate group relative to the corresponding 1-phosphate group in Ins(1,4,5)P3. To investigate this possibility, two bicyclic trisphosphates 9 and 10, designed to explore the effect of relocating the 1-phosphate group of Ins(1,4,5)P3 using a novel fused-ring system, were synthesized from myo-inositol. Biological evaluation of 9 and 10 at the Ins(1,4,5)P3 receptors of hepatocytes showed that both were recognized by hepatic Ins(1,4,5)P3 receptors and both stimulated release of Ca²⁺ from intracellular stores, but they had lower affinity than Ins(1,4,5)P3. This finding may be explained by considering the three-dimensional structures of 9 and 10 in light of recent studies on the conformation of adenophostin A.

Adenophostin A is the most potent known agonist of inositol 1,4,5-trisphosphate (InsP(3)) receptors. Ca(2+) release from permeabilized hepatocytes was 9.9 +/- 1.6-fold more sensitive to adenophostin A (EC(50), 14.7 +/- 2.4 nM) than to InsP(3) (145 +/- 10 nM), consistent with the greater affinity of adenophostin A for hepatic InsP(3) receptors (K(d) = 0.48 +/- 0.06 and 3.09 +/- 0.33 nM, respectively). Here, we systematically modify the structures of the glucose, ribose, and adenine moieties of adenophostin A and use Ca(2+) release and binding assays to define their contributions to high-affinity binding. Progressive trimming of the adenine of adenophostin A reduced potency, but it fell below that of InsP(3) only after complete removal of the adenine. Even after substantial modifications of the adenine (to uracil or even unrelated aromatic rings, retaining the beta-orientation), the analogs were more potent than InsP(3). The only analog with an alpha-ribosyl linkage had massively decreased potency. The 2'-phosphate on the ribose ring of adenophostin A was essential and optimally active when present on a five-membered ring in a position stereochemically equivalent to its location in adenophostin A. Xylo-adenophostin, where xylose replaces the glucose ring of adenophostin A, was only slightly less potent than adenophostin A, whereas manno-adenophostin (mannose replacing glucose) had similar potency to InsP(3). These results are consistent with the relatively minor role of the 3-hydroxyl of InsP(3) (the equivalent is absent from xylo-adenophostin) and greater role of the equatorial 6-hydroxyl (the equivalent is axial in manno-adenophostin). This is the first comprehensive analysis of all the key structural elements of adenophostin A, and it provides a working model for the design of related high-affinity ligands of InsP(3) receptors.

Plasma renin activity (PRA), active renin (AR), prorenin, and angiotensinogen were assessed in 486 hypertensive and 175 normotensive subjects with a sodium intake of 10 or 200 mEq/d during supine and upright posture and after infusion of angiotensin II. PRA and AR levels were compared in hypertensive subjects in each condition. With low sodium intake, particularly while upright, there was a significant correlation between PRA and AR. In upright subjects with low sodium intake who had a PRA of 2.4 ng/mL per hour or less (1.85 nmol.L-1.h-1 or less), the correlation was also strong. With high sodium intake, the correlation was weaker. With intermediate sodium excretion, the correlation was intermediate. Prorenin was less predictive of PRA than was AR, and angiotensinogen had a marginal role. Using PRA during sodium restriction while upright as the standard for determining renin status, the precision of AR for predicting renin status was excellent. AR may be used for surrogate assessment of the renin-angiotensin system activity when the system is activated.

Syntheses of 3‘-O-α-d-glucopyranosyl-1-β-d-ribofuranosidoimidazole 2‘,3‘ ‘,4‘ ‘-trisphosphate (7) and 3‘-O-α-d-glucopyranosyl-9-β-d-ribofuranosidopurine 2‘,3‘ ‘,4‘ ‘-trisphosphate (8), two analogues of the superpotent 1d-myo-inositol 1,4,5-trisphosphate receptor agonist adenophostin A (2), are described. 5-O-Benzyl-1,2-O-isopropylidene-α-d-ribofuranose was prepared by an improved route from 1,2-O-isopropylidene-α-d-xylofuranose and was coupled with 3,4-di-O-acetyl-2,6-di-O-benzyl-d-glucopyranosyl dimethyl phosphite to give 3‘,4‘-di-O-acetyl-2‘,5,6‘-tri-O-benzyl-3-O-α-d-glucopyranosyl-1,2-O-isopropylidene-α-d-ribofuranose. Removal of the isopropylidene acetal and subsequent acetylation gave the central disaccharide 1,2,3‘,4‘-tetra-O-acetyl-2‘,5,6‘-tri-O-benzyl-3-O-α-d-glucopyranosyl-d-ribofuranose. Vorbrüggen condensation with activated imidazole or purine gave the required β-substituted derivatives which were further elaborated to 7 and 8, respectively. Radioligand binding assays to hepatic InsP3 receptors and functional assays of Ca²⁺ release from permeabilized hepatocytes gave a rank order of potency of the ligands 2 ≈ 8 > 7 ≈ Ins(1,4,5)P3 indicating that the N⁶-amino group of 2 is of little importance for activity and that a minimum of a two-fused-ring nucleobase is required for activity to exceed that of Ins(1,4,5)P3. The role of the adenine base in the activity of the adenophostins is discussed. This general method should facilitate ready access to nucleobase-modified adenophostin analogues for SAR studies.

Clustered disaccharide analogues of adenophostin A (2), i.e. mono-, di-, and tetravalent derivatives 6−8, respectively, were synthesized and evaluated as novel ligands for the tetrameric d-myo-inositol 1,4,5-trisphosphate receptor (IP3R). The synthesis was accomplished via Sonogashira coupling of propargyl 2-O-acetyl-5-O-benzyl-3-O-(3,4-di-O-acetyl-2,6-di-O-benzyl-α-d-glucopyranosyl)-β-d-ribofuranoside (16) with iodobenzene 18, 22, or 25, followed by deacetylation, phosphorylation, and deprotection. The abilities of the target compounds 6−8, as well as ribophostin 4, propylphostin 5, and IP3 (1), to evoke Ca²⁺ release from permeabilized hepatocytes or displacement of [³H]IP3 from its receptor in hepatic membranes were compared. Although the binding affinities of 4−8 were similar, there were modest though significant differences in their potencies in Ca²⁺ release assays:  tetraphostin 8 > IP3 ~ diphostin 7 > phenylphostin 6 > ribophostin 4 ~ propylphostin 5.

Racemic mixtures and enantiomerically pure D-isomers of both myo-inositol 1,3,6-trisphosphorothioate [Ins(1,3,6)PS(3)] and myo-inositol 1,4,6-trisphosphorothioate [Ins(1,4,6)PS(3)], prepared by total synthesis, were examined in Ca(2+) flux and binding assays. Both D-Ins(1,3,6)PS(3) and D-Ins(1,4,6)PS(3) were shown to be low intrinsic activity partial agonists at the platelet myo-inositol 1,4, 5-trisphosphate [Ins(1,4,5)P(3)] receptor, releasing less than 20% of the Ins(1,4,5)P(3)-sensitive Ca(2+) store. D-Ins(1,4,6)PS(3) displaced specifically bound [(3)H]Ins(1,4,5)P(3) from rat cerebellar membranes, although displacement was some 34-fold weaker than by D-Ins(1,4,5)P(3). D-Ins(1,4,6)PS(3) displaced [(3)H]Ins(1,4, 5)P(3) from cerebellar membranes with roughly twice the affinity of DL-Ins(1,4,6)PS(3) (IC(50) value = 1.4 +/- 0.35 microM compared with 2.15 +/- 0.13 microM), whereas D-Ins(1,3,6)PS(3) displaced [(3)H]Ins(1,4,5)P(3) with roughly twice the affinity of DL-Ins(1,3, 6)PS(3) (IC(50) value = 17.5 +/- 5.8 microM compared with 34 +/- 10 microM), confirming that the activity of both these phosphorothioates resides in their D-enantiomers. Increasing concentrations of either D-Ins(1,3,6)PS(3) or D-Ins(1,4,6)PS(3) were able to partially antagonize Ca(2+) release induced by submaximal concentrations of Ins(1,4,5)P(3), an inhibition that could be overcome by increasing the concentration of Ins(1,4,5)P(3), suggesting competition for binding at the Ins(1,4,5)P(3)-R. The only low-efficacy partial agonists at the Ins(1,4,5)P(3)-R discovered to date have been phosphorothioates; the novel D-Ins(1,3,6)PS(3) and D-Ins(1,4,6)PS(3) can now be added to this small group of analogs. However, D-Ins(1,4,6)PS(3) has a relatively high affinity for the Ins(1,4,5)P(3)-R but maintains the lowest efficacy of all the partial agonists thus far identified. As such, it may be a useful tool for pharmacological intervention in the polyphosphoinositide pathway and an important lead compound for the development of further Ins(1,4,5)P(3)-R antagonists.

Subpontic osseous hyperplasia has been portrayed in both the historical and the current literature as occurring exclusively in the mandibular posterior region. This article presents the clinical, radiologic, and microscopic documentation of subpontic osseous hyperplasia occurring in the maxillary first molar region.

Positron emission tomography (PET) myocardial perfusion imaging (MPI) is a well-validated non-invasive imaging technique for the assessment of coronary artery disease (CAD). Amongst its many advantage, it permits quantitative, non-invasive assessment of myocardial blood flow (MBF) and myocardial flow reserve (MFR). While the diagnostic and prognostic value of MFR has been extensively validated in the general CAD population, only limited data is available when it comes to its prognostic value in patients with prior coronary artery bypass grafting (CABG). Our study aim was to evaluate if diminished MFR on 13N-Ammonia PET MPI is associated with increased risk of major adverse cardiovascular events (MACE) amongst patients with prior CABG.

The Institut national d'excellence en santé et en services sociaux (INESSS) has collaborated with Québec's transcatheter aortic valve implantation (TAVI) programs since 2013 to evaluate processes of care and outcomes. In 2018-2019, data were also collected on surgical aortic valve replacement (SAVR). Herein, we describe real-world volume and outcome trends for these two patient groups, as well as processes of care and clinical characteristics over a 6-month period.

The addition of low-dose rivaroxaban to aspirin in patients with stable atherosclerotic disease has been shown effective in reducing ischemic events. However, what proportion of cardiology patients might be deemed eligible for such therapy remains uncertain. We aimed to estimate the rate of eligibility among cardiology outpatients at an academic tertiary care center.

Post-myocardial infarction (Post-MI) cardiogenic shock (CS) is a serious life-threatening condition that requires complex coordinated care. Despite this, early mortality remains as high as 50%, likely owing to still inadequate understanding of pathophysiology and the potential benefits of percutaneous ventricular assist devices (pVADs). Although all pVADs increase circulatory flow, they vary in their ability to help restore cardiac pump function. Additionally, shortcomings in terms of our understanding of the optimal timing of such devices in STEMI and shock algorithms likely contributes to the high mortality. Currently, preclinical pVAD evaluation is limited by the need for animal research where the induction of CS is often lethal before devices can be tested. We therefore plan to develop a high-fidelity simulator to facilitate device evaluation and help train clinical teams. The first phase to this program requires the elaboration of a stable animal post-MI CS model that can generate the physiologic data necessary for simulator validation.

Src homology 2 (SH2) domains exist in many intracellular proteins and have well characterized roles in signal transduction. SH2 domains bind to phosphotyrosine (Tyr(P))-containing proteins. Although tyrosine phosphorylation is essential for protein-SH2 domain interactions, the binding specificity also derives from sequences C-terminal to the Tyr(P) residue. The high affinity and specificity of this interaction is critical for precluding aberrant cross-talk between signaling pathways. The p85alpha subunit of phosphoinositide 3-kinase (PI 3-kinase) contains two SH2 domains, and it has been proposed that in competition with Tyr(P) binding they may also mediate membrane attachment via interactions with phosphoinositide products of PI 3-kinase. We used nuclear magnetic resonance spectroscopy and biosensor experiments to investigate interactions between the p85alpha SH2 domains and phosphoinositides or inositol polyphosphates. We reported previously a similar approach when demonstrating that some pleckstrin homology domains show binding specificity for distinct phosphoinositides (Salim, K., Bottomley, M. J., Querfurth, E., Zvelebil, M. J., Gout, I., Scaife, R., Margolis, R. L., Gigg, R., Smith, C. I., Driscoll, P. C., Waterfield, M. D., and Panayotou, G. (1996) EMBO J. 15, 6241-6250). However, neither SH2 domain exhibited binding specificity for phosphoinositides in phospholipid bilayers. We show that the p85alpha SH2 domain Tyr(P) binding pockets indiscriminately accommodate phosphoinositides and inositol polyphosphates. Binding of the SH2 domains to Tyr(P) peptides was only poorly competed for by phosphoinositides or inositol polyphosphates. We conclude that these ligands do not bind p85alpha SH2 domains with high affinity or specificity. Moreover, we observed that although wortmannin blocks PI 3-kinase activity in vivo, it does not affect the ability of tyrosine-phosphorylated proteins to bind to p85alpha. Consequently phosphoinositide products of PI 3-kinase are unlikely to regulate signaling through p85alpha SH2 domains.