Malnutrition and cachexia are associated with poor CAR T-cell therapy outcomes including survival.

BACKGROUND & AIMS: Chimeric Antigen Receptor (CAR) T-cell therapy has emerged as a revolutionary treatment for patients with refractory or relapsed B-cell malignancies. However, a significant proportion of patients experience negative outcomes, including severe inflammatory toxicities and relapse. Cachexia and malnutrition are known secondary syndromes in many cancer patients, attributed to the effects of active malignancy, systemic inflammation, and cumulative treatment burden; however, further research is required to accurately characterise these issues in CAR T-cell patients. The aims of this service evaluation were to explore the changes in nutritional status (malnutrition and cachexia) in CAR T-cell therapy patients and the potential impact on patient outcomes including survival. Additionally, we describe the utilisation of dietetic resources in this specific patient population in a London tertiary referral centre. METHODS: Adult haematology patients receiving licensed CD19-targeting CAR T-cell therapy at University College London Hospital between 01/04/19 and 01/09/21 were included. Data were collected from the time of treatment consent, and throughout admission to day of discharge: body weight (BW), C-reactive protein, albumin, lactate dehydrogenase, nutrition-risk screening scores (hospital-specific) and dietetic input. Clinical outcomes such as 12-month all-cause mortality, intensive care unit (ICU) admission, high-grade toxicities, and length of hospital stay (LoS) were also recorded. Cachexia and malnutrition were defined using the modified Glasgow Prognostic Score (mGPS) and Global Leadership Initiative on Malnutrition (GLIM) consensus, respectively. RESULTS: 114 patients (55.6 ± 15.1 years; 57% males) with B-cell non-Hodgkin's lymphoma (n = 109) and B-cell acute lymphoblastic leukaemia (n = 5), receiving axicabtagene ciloleucel (n = 89) and tisagenlecleucel (n = 25) were included. Median LoS for treatment was 34 (27-38) days. Prior to treatment, 31.5% of patients developed malnutrition, with pre-cachexia/refractory cachexia (mGPS) identified in 43.6% of patients. This altered nutritional status pre-treatment was significantly associated with adverse patient outcomes post-infusion; mGPS was independently associated with inferior overall survival (HR = 3.158, CI = 1.36-7.323, p = 0.007), with malnutrition and mGPS associated with increased LoS (p = 0.037), sepsis (p = 0.022) and ICU admission (p = 0.039). During admission, patients experienced significant BW loss (-5.6% (-8.8 to -2.4); p=<0.001), with 68.4% developing malnutrition. Malnutrition screening during admission identified 57% patients at-risk, with 66.6% of patients referred to dietetics; however, there was a lack of malnutrition screening and dietetic referrals prior to treatment. CONCLUSION: Pre-treatment malnutrition and cachexia was significantly associated with adverse CAR T patient outcomes, including mGPS cachexia status independently associated with inferior overall survival. Further research in this novel space is essential to confirm the extent and impact of nutritional issues, to assist with implementing dietetic pathways, and to identify potential interventions with a view to optimising outcomes.

Sarcopenic Obesity and Depression: A Systematic Review.

BACKGROUND: Sarcopenic obesity (SO) is a condition combining two important public health issues commonly seen amongst older individuals, obesity and sarcopenia. Depressive symptoms are common among older people, whose population is increasing worldwide. Obesity and sarcopenia alone, are clearly associated with depression while the coexistence of these two conditions (SO) upon depressive disorders is currently unclear. We aimed to systematically review the association between primary SO and depressive disorders. METHODS: Searches were run on MEDLINE, EMBASE, PsycINFO, and CINAHL (inception to June 2019). One reviewer screened titles, abstracts, and full-texts, with 10% checked independently by a second reviewer. Cohort and cross-sectional studies were included. Two reviewers independently assessed risk of bias using the Mixed Methods Appraisal Tool. Results were narratively synthesised. RESULTS: Out of the 7 studies eligible for inclusion, evidence of sarcopenic obesity as a predictor of depressive symptoms was found in two studies. The main observed trend was that diagnosing sarcopenia using muscle strength led to significant associations between sarcopenic obesity and depressive symptoms. Two cross-sectional studies found a significant association between SO and depressive symptoms, whilst three others found no statistically significant associations. All possessed some methodological limitations. DISCUSSION: This is the first review to systematically examine a potential relationship between sarcopenic obesity and depressive disorders. Currently, the results are heterogeneous due to the large variability in assessment methods and outcome measurements. Future longitudinal studies would achieve greater confidence in the provisional conclusion that sarcopenic obesity, when measured using muscle strength, is associated with depressive symptoms.

Predictors of hearing threshold levels and distortion product otoacoustic emissions among noise exposed young adults.

AIM: To examine the relations between noise exposure and other risk factors with hearing function as measured by audiometric thresholds and distortion product otoacoustic emissions. METHODS: A total of 456 subjects were studied (393 apprentices in construction trades and 63 graduate students). Hearing and peripheral auditory function were quantified using standard, automated threshold audiometry, tympanometry, and distortion product otoacoustic emissions (DPOAEs). The analysis addressed relations of noise exposure history and other risk factors with hearing threshold levels (HTLs) and DPOAEs at the baseline test for the cohort. RESULTS: The cohort had a mean age of 27 (7) years. The construction apprentices reported more noise exposure than students in both their occupational and non-occupational exposure histories. A strong effect of age and years of work in construction was observed at 4, 6, and 8 kHz for both HTLs and DPOAEs. Each year of construction work reported prior to baseline was associated with a 0.7 dB increase in HTL or 0.2 dB decrease DPOAE amplitude. Overall, there was a very similar pattern of effects between the HTLs and DPOAEs. CONCLUSIONS: This analysis shows a relatively good correspondence between the associations of noise exposures and other risk factors with DPOAEs and the associations observed with pure-tone audiometric thresholds in a young adult working population. The results provide further evidence that DPOAEs can be used to assess damage to hearing from a variety of exposures including noise. Clarifying advantages of DPOAEs or HTLs in terms of sensitivity to early manifestations of noise insults, or their utility in predicting future loss in hearing will require longitudinal follow up.

Oxazolidinones mechanism of action: inhibition of the first peptide bond formation.

Oxazolidinones are potent inhibitors of bacterial protein biosynthesis. Previous studies have demonstrated that this new class of antimicrobial agent blocks translation by inhibiting initiation complex formation, while post-initiation translation by polysomes and poly(U)-dependent translation is not a target for these compounds. We found that oxazolidinones inhibit translation of natural mRNA templates but have no significant effect on poly(A)-dependent translation. Here we show that various oxazolidinones inhibit ribosomal peptidyltransferase activity in the simple reaction of 70 S ribosomes using initiator-tRNA or N-protected CCA-Phe as a P-site substrate and puromycin as an A-site substrate. Steady-state kinetic analysis shows that oxazolidinones display a competitive inhibition pattern with respect to both the P-site and A-site substrates. This is consistent with a rapid equilibrium, ordered mechanism of the peptidyltransferase reaction, wherein binding of the A-site substrate can occur only after complex formation between peptidyltransferase and the P-site substrate. We propose that oxazolidinones inhibit bacterial protein biosynthesis by interfering with the binding of initiator fMet-tRNA(i)(Met) to the ribosomal peptidyltransferase P-site, which is vacant only prior to the formation of the first peptide bond.

Regulation of gene expression and cell growth in vivo by tetracycline using the hollow fiber assay.

The hollow fiber assay presents a potentially unique tool to study the effects of regulated gene expression in cell lines that do not form tumors in vivo. The hollow fibers allow small molecules to pass freely through while keeping the cells within the fibers and segregated from host cells. OSp16.1 cells, derived from the U24 clone of the U2-OS osteogenic sarcoma tumor line, express the p16INK4a tumor suppressor under the regulation of tetracycline (tet) (Mitra J et al. Mol Cell Bio 19:3916, 1999). The in vitro induction of p16 in the OSp16.1 cell line is regulated by tet. The hollow fiber assay was used to determine whether the regulation of the p16 gene could be achieved in vivo, since these cells did not grow in the xenograft model. There were no differences in the in vivo growth pattern of U24 cells loaded into the hollow fibers with and without tet: 807% and 839% net growth, respectively. OSp16.1 cells in fibers in mice receiving 3.33 mg/kg/day tet had a 644% net growth after 21 days. There was a 194% net growth without tet. Immunoblotting of extracts prepared from the hollow fibers confirmed that p16 was induced in the absence of tet. These data demonstrate this assay is a useful tool for studying the effects of regulated gene expression in vivo.

Platelet GPIIb/IIIa binding characteristics of small molecule RGD mimetic: distinct binding profile for Roxifiban.

A number of non-peptide orally active RGD mimetic prodrug such as Orbofiban, Sibrafiban, SR121566, Roxifiban and others entered into the clinical evaluation stage. Some of these agents were terminated and some are still in clinical trials. The present study examined the platelet GPIIb/IIIa binding profiles for the active form of Roxifiban, Sibrafiban, SR121566 and Orbofiban using 3H-Roxifiban active form (XV459), 3H-DMP728, 125I-Echistatin, and 125I-Fibrinogen. Either DMP728, Orbofiban, Sibrafiban, SR121566 or Roxifiban active form as well as other RGD mimetic bind to the same binding site(s) on human platelets as evident from the competitive inhibition of binding of each other to human platelet. Additionally, Roxifiban active form competed with FITC labeled GPIIb/IIIa antagonist cyclic RGD peptidomimetic (XL086) as demonstrated using confocal microscopy technique. Roxifiban active form (XV459) demonstrated the highest potency in inhibiting 3H-XV459, 3H-DMP728, 125I-Echistatin, and 125I-Fibrinogen binding to human platelets as compared to the others. Structure activity relationship within the isoxazoline Roxifiban series showed that substituent at the alpha-carbon next to the carboxy terminal represents an exosite for the affinity binding to human platelets leading to slow platelet dissociation rate. These data indicated a distinct binding profile for Roxifiban (high affinity to both activated and resting platelets associated with a relatively slow K(off)) as compared to others. These differences might determine the pharmacodynamics and pharmackokinetics of the different GPIIb/IIIa antagonists.

Alpha(v)beta(3) integrin in angiogenesis and restenosis.

Various integrins are thought to be intimately involved in several pathological processes, including cancers (solid tumors and metastasis), cardiovascular diseases (stroke and heart failure), inflammatory diseases (rheumatoid arthritis) and ocular pathologies. The mechanism of the involvement of integrins in these acute and chronic disease states is slowly being elucidated. Recently, various therapeutic candidates, including antibodies, cyclic peptides and peptidomimetics, have been clinically evaluated and have been shown to successfully modulate certain disease processes. This review focuses on the key role of the alpha(v) integrin (alpha(v)beta(3)) in the angiogenic processes in diseases such as cancer, restenosis following percutaneous transluminal coronary angioplasty, stroke, ocular disease and rheumatoid arthritis.

Small molecule alpha(v) integrin antagonists: novel anticancer agents.

The members of the integrin family are targets that potentially provide both therapeutic and diagnostic opportunities. Advances in the understanding of the signalling pathways, transcriptional regulation and the structure/function relationships of the adhesion molecules to extracellular matrix proteins have all contributed to these opportunities. The role of the integrins in pathological processes in both acute and chronic diseases, include ocular, cancer (solid tumours and metastasis), cardiovascular (stroke and heart failure) and inflammatory (rheumatoid arthritis) conditions. Various therapeutic candidates, including antibodies, cyclic peptides and peptidomimetics, have been identified. This review will focus on the key role of the alpha(v) integrin (alpha(v)beta(3) and alpha(v)beta(5)) in angiogenic processes in tumours, including its potential use in cancer diagnostics and therapy.

Nonpeptide factor Xa inhibitors II. Antithrombotic evaluation in a rabbit model of electrically induced carotid artery thrombosis.

SK549 (mol. wt. 546 Da) is a synthetic, selective inhibitor of human coagulation factor Xa (fXa) (K(i) = 0.52 nM). This study compared the antithrombotic effects of SK549 and a series of benzamidine isoxazoline fXa inhibitors with aspirin, DuP 714 (a direct thrombin inhibitor), recombinant tick anticoagulant peptide, or heparin in a rabbit model of electrically induced carotid arterial thrombosis. Compounds were infused i.v. continuously from 60 min before electrical stimulation to the end of the experiment. Values of ED(50) (dose that increases the carotid blood flow to 50% of the control) were 0.12 micromol/kg/h for SK549, 0.56 micromol/kg/h for aspirin, 0.14 micromol/kg/h for DuP 714, 0.06 micromol/kg/h for recombinant tick anticoagulant peptide, and >100 U/kg/h for heparin. The EC(50) (plasma concentration that increased blood flow to 50% of the control) for SK549 was 97 nM. Unlike aspirin and heparin, SK549 was efficacious and, at 1.5 micromol/kg/h i.v. (n = 9), maintained carotid blood flow at 87 +/- 6% of control level for greater than 90 min. Unlike heparin, SK549 inhibited ex vivo fXa activity but not ex vivo thrombin activity. There was a highly significant correlation between K(i) (fXa) and ED(50) of a series of fXa inhibitors (r = 0. 85, P <.001). Therefore, these results suggest that SK549 is a novel, potent, and effective antithrombotic agent in a rabbit model of arterial thrombosis. It is likely that SK549 exerts its antithrombotic effect through selective inhibition of fXa. Furthermore, SK549 may be clinically useful for the prevention of arterial thrombosis.

Differential antiplatelet efficacy for various GPIIb/IIIa antagonists: role of plasma calcium levels.

OBJECTIVES: The present study was undertaken to determine the effects of free ionized calcium influenced by either the anticoagulant used (citrate vs. heparin) or directly varying the calcium levels after treatment of blood with citrate on the antiplatelet efficacy of two classes of GPIIb/IIIa antagonists. METHODS: The platelet effects of changes in plasma [Ca(++)] with the different GPIIb/IIIa antagonists were determined using light transmittance aggregometry, direct binding kinetics, and (125)I-fibrinogen binding to activated human platelets. RESULTS: A significantly higher IC50s was shown with heparin (free ionized calcium=1.1 mM) as compared to that with citrate (free ionized calcium=0.12 mM) with class II GPIIb/IIIa antagonists (P<0.01) such as Orbofiban, and Integrilin. In contrast, class I GPIIb/IIIa antagonists such as Roxifiban and Abciximab showed no significant changes in their IC50s in either citrate or heparin. Similar data were shown with other non-calcium chelating anticoagulant such as PPACK as compared to that with heparin. Additionally, similar data were shown with regard to the [Ca(++)] sensitivity for GPIIb/IIIa antagonists from Class II but not Class I in the changes in IC50 values required for the inhibition of (125)I-fibrinogen binding to activated human gel filtered platelets. Additionally, examples from Class I GPIIb/IIIa antagonists such as (3)H-active form of Roxifiban showed no significant changes in its platelet binding affinity in response to change in [Ca(++)]. In contrast, GPIIb/IIIa antagonists from class II such as (3)H-active form of Orbofiban demonstrated significant changes (P<0.01) in its platelet binding kinetics and antiplatelet efficacy in response to changes in Ca(++) concentrations. CONCLUSIONS: These data suggest the impact of the method of blood collection or changes in plasma calcium levels on the antiplatelet efficacy for class II but not class I GPIIb/IIIa antagonists depending on their platelet binding kinetics.

Tumor biology: use of tiled images in conjunction with measurements of cellular proliferation and death in response to drug treatments.

Tumor growth is dependent on the balance between cell proliferation and cell death, and these events occur heterogenously within an individual tumor. We present a methodology that provides integrative information about cell kinetics, cell death, and cell growth within individual tumors in animals treated with cytotoxic chemotherapeutic agents. Using HCT-116 and NCI-H460 cells, human colonic adenocarcinoma and non-small cell lung cells, respectively, traditional xenograft studies were performed. The tumor-bearing animals were treated with cyclophosphamide (Cytoxan), gemcitabine (Gemzar), or mitomycin C, and extensive analysis of the tumors was studied. Cell kinetics were evaluated by measuring the apoptotic and proliferation indices. The ability to image an entire tumor section using "tiling" by creating a large montage from many high-resolution images makes it possible to identify regional differences within areas of tumor and to demonstrate differences in these tumor regions after treatment with selected chemotherapeutic agents. Two specific areas within tumors have been identified: (a) areas of viable cells within the cell cycle, determined by bromodeoxyuridine and/or morphological characteristics determined by hematoxylin staining; and (b) areas of necrosis determined by the absence of bromodeoxyuridine and proliferating cell nuclear antigen-labeled cells coupled with morphological changes. By standardizing the tumor size to 100 mm2, different patterns of tumor responses to chemotherapeutic agents were determined. By creating such tiled images and by quantitating cell cycle kinetics, it is possible to gain a more complete understanding of tumor growth and response to treatment, leading to the development of more reliable methods for assessing the clinical behavior of anticancer drugs.

Helicobacter pylori-selective antibacterials based on inhibition of pyrimidine biosynthesis.

We report the discovery of a class of pyrazole-based compounds that are potent inhibitors of the dihydroorotate dehydrogenase of Helicobacter pylori but that do not inhibit the cognate enzymes from Gram-positive bacteria or humans. In culture these compounds inhibit the growth of H. pylori selectively, showing no effect on other Gram-negative or Gram-positive bacteria or human cell lines. These compounds represent the first examples of H. pylori-specific antibacterial agents. Cellular activity within this structural class appears to be due to dihydroorotate dehydrogenase inhibition. Minor structural changes that abrogate in vitro inhibition of the enzyme likewise eliminate cellular activity. Furthermore, the minimum inhibitory concentrations of these compounds increase upon addition of orotate to the culture medium in a concentration-dependent manner, consistent with dihydroorotate dehydrogenase inhibition as the mechanism of cellular inhibition. The data presented here suggest that targeted inhibition of de novo pyrimidine biosynthesis may be a valuable mechanism for the development of antimicrobial agents selective for H. pylori.

Selective inhibition of bacterial dihydroorotate dehydrogenases by thiadiazolidinediones.

Dihydroorotate dehydrogenase is a critical enzyme of de novo pyrimidine biosynthesis in prokaryotic and eukaryotic cells. Differences in the primary structure of the enzymes from Gram-positive and -negative bacteria and from mammals indicate significant structural divergence among these enzymes. We have identified a class of small molecules, the thiadiazolidinediones, that inhibit prototypical enzymes from Gram-positive and -negative bacteria, but are inactive against the human enzyme. The most potent compound in our collection functioned as a time-dependent irreversible inactivator of the bacterial enzymes with k(inact)/K(i) values of 48 and 500 M(-1) sec(-1) for the enzymes from Escherichia coli and Enterococcus faecalis, respectively. The data presented here indicate that it is possible to inhibit prokaryotic dihydroorotate dehydrogenases selectively while sparing the mammalian enzyme. Thus, this enzyme may represent a valuable target for the development of novel antibiotic compounds.

The hollow fiber assay: continued characterization with novel approaches.

The hollow fiber assay, a unique in vivo model, permits the simultaneous evaluation of compound efficacy against multiple cell lines in two physiological compartments. This assay has been used to characterize in vivo activity of cytotoxic compounds. The purpose of the present study was to characterize and optimize this assay for compounds with a defined mechanism of action, specifically cell cycle inhibition. Two human tumor cell lines and one normal human cell line were loaded into polyvinylidene fluoride hollow fibers at two or more cell concentrations and grown in mice for 3-10 days. The data demonstrate the importance of characterizing the initial loading density of various cell lines in the evaluation of compounds. All studies were performed with cells in the linear part of the cell growth curves. Initial loading densities of 1-2 x 10(4) cells/fiber gave the greatest opportunity for growth in the three human cell lines tested (HCT116 colon carcinoma, NCI-H460 non-small cell carcinoma, and AG 1523 normal fibroblast). Utilizing the MTT assay, standard curves were constructed to correlate the final number of cells with optical density (OD) readings at 540 nm in order to calculate cell numbers in the fibers. Insights into the mechanism of action of cisplatin have been gained using Western blot analysis of the cell cycle markers PCNA (a protein present throughout the cell cycle) and Rb (a protein that acts as a tumor suppressor gene product) from the hollow fiber cells. In cisplatin-treated NCI-H460 cells both PCNA and Rb phosphorylation decreased, suggesting the arrest of the cells prior to the S phase. Standard therapeutic agents, cisplatin, racemic flavopiridol, cyclophosphamide and mitomycin C, were evaluated independently in the hollow fiber assay and the xenograft model. The data demonstrate that compounds active in the hollow fiber assay are also active in the xenograft.

Novel small molecule alpha v integrin antagonists: comparative anti-cancer efficacy with known angiogenesis inhibitors.

Recent evidence supports the involvement of integrins in angiogenesis: blockade of alpha v beta 3 and alpha v beta 5 integrins disrupts angiogenesis leading to decreased blood vessel formation and hence decreased tumor growth. We hypothesized that av antagonists could inhibit tumor growth in tumor cells devoid of alpha v beta 3 integrins. We evaluated SM256 and SD983, novel small molecules that are specific av antagonists in mouse models of angiogenesis and tumorigenesis, and compared them with standards: TNP470, a fumagillin analog in the clinic, and flavopiridol, a cell cycle kinase inhibitor. In vitro SM256 was a selective alpha v beta 3 inhibitor with an IC50 = 4nM, and the affinity of SD983 against the mouse endothelial alpha v beta 3 integrin yielded an IC50 = 2nM and an IC50 = 54nM against alpha v beta 5. In the mouse Matrigel model of angiogenesis SM256 decreased blood vessel formation (hemoglobin content) with an ED50 = 0.055 ug/kg/day, tenfold more potent than TNP470. SG545, an ester of SD983, decreased blood vessel formation with an ED50 = 6 ug/kg/day, while flavopiridol ED50 = 18 ug/kg/day. In the mouse xenograft model, using human colon carcinoma RKO cells that do not express alpha v beta 3 but express alpha v beta 5, tumor growth was inhibited by SG545 (10 mg/kg/day) and flavopiridol (5 mg/kg/every other day) 40% and 70%, respectively (p < 0.05). Although the proliferative index (measured by BrdU incorporation) was not significantly changed with SM256, SG545 or flavopiridol (29-32%), the apoptotic index increased significantly (p < 0.05) in the SM256 and SG545-treated groups (2.3-2.7%) compared with controls (1.1%), suggesting increased cell death contributed to decreased tumor volumes. Neovascularization decreased with SM256 and SG545 treatment. The data demonstrate that potent selective av antagonist can target endothelial cells, tumor cells, inhibit angiogenesis and inhibit tumor growth.

Vascular endothelial growth factor in porcine coronary arteries following balloon angioplasty.

The present study was a preliminary inquiry into the presence of vascular endothelial growth factor (VEGF) in a model of coronary artery response to injury. We examined domestic pigs who had received a diet enriched in saturated fat and cholesterol and undergone balloon angioplasty of one or more coronary arteries. Immunohistochemical analysis of the coronary arteries 2 months after injury revealed the presence of VEGF distributed throughout the media and neointima of the angioplasty lesions and in association with blood vessels in the adventitia and those vessels growing into the base of the neointima. VEGF was also detected in areas of dietary-induced intimal proliferation. This study provided the first immunochemical demonstration of VEGF occuring naturally in a pig model of coronary response to injury.

Antiplatelet efficacy of XV459, a novel nonpeptide platelet GPIIb/IIIa antagonist: comparative platelet binding profiles with c7E3.

Recent advances in the development of i.v. platelet glycoprotein alphaIIb/beta3 integrin (GPIIb/IIIa) antagonists led to the development of either a class of small-molecular-weight antagonists with a short to ultra-short duration of antiplatelet effects (Integrelin, Tirofiban, DMP728) or a very long-acting antagonist (ReoPro). Thus the present study was undertaken to characterize the antiplatelet efficacy of a small-molecule GPIIb/IIIa antagonist, DMP754/XV459, and to determine its platelet GPIIb/IIIa receptor binding profiles. DMP754, upon its conversion with esterases to its free acid form XV459, and XV459 itself, demonstrated high potency (IC50 = 0.030-0.060 microM) in inhibiting human platelet aggregation induced by ADP (100 microM), thrombin receptor agonist peptide (10 microM) or collagen (20 microgram/ml) in citrate or heparin. Maximal platelet aggregation inhibition was achieved at 50 to >/=80% receptor occupancy, depending on the agonist used. Both XV459 and c7E3 bind with high affinity to either activated human platelets (Kd = 0.0008 and 0.0091 microM, respectively) or unactivated human platelets (Kd = 0.0025 and 0.0092 microM, respectively). XV459 demonstrated tight association with human, baboon and (to a lesser extent) canine platelets (t1/2 of dissociation = 7 +/- 0, 8 +/- 1 and 1.4 +/- 0.1 minutes, respectively). Both c7E3 and XV459 associate tightly with slower dissociation rates to unactivated human platelets. XV459 represents a potent antiplatelet agent in inhibiting platelet aggregation along with offering high affinity and a relatively slow dissociation rate from human platelet GPIIb/IIIa receptors that might allow for once-a-day p.o. dosage.

Oral antiplatelet efficacy and specificity of a novel nonpeptide platelet GPIIb/IIIa receptor antagonist, DMP 802.

This study was undertaken to define the platelet glycoprotein alphaIIb beta3 integrin (GPII/IIIa) affinity, specificity, and oral antiplatelet efficacy of DMP 802, a small-molecule nonpeptide antiplatelet agent. Platelet GPIIb/IIIa integrin binding affinity and specificity for DMP 802 were determined by using binding and adhesion assays with cells from various species, including human. DMP 802 demonstrated a potent antiplatelet efficacy [median inhibitory concentration (IC50), 0.029 +/- 0.0042 microM] in inhibiting human platelet aggregation induced by 10 microM adenosine diphosphate (ADP), as assessed by light-transmittance aggregometry. DMP 802 inhibited 125I-fibrinogen binding to activated (ADP, epinephrine, and arachidonic acid at 100 microM each) gel purified human platelets with an IC50 of 0.012 +/- 0.003 microM. DMP 802 demonstrated tight association with unactivated human, baboon, or canine platelets (t(1/2) of dissociation, 32 +/- 2, 32 +/- 13, and 11 +/- 1 min, respectively). DMP 802 binds with high affinity to both unactivated and activated human platelets (Kd = 0.61 +/- 0.17, 0.57 +/- 0.21 nM, respectively). DMP 802 demonstrated species specificity in inhibiting platelet aggregation with IC50 values ranging from 0.025 to 0.092 microM (human, guinea pig, dog, swine, hamster) and 0.88-1.0 microM (rabbit and rat) in platelets obtained from these various species. DMP 802 demonstrated a high degree of specificity for platelet GPIIb/IIIa (alphaIIb/beta3) as compared with other integrins including alpha(v)beta3 (IC50, >10 microM), alpha(v)beta5 (IC50, >100 microM), alpha4beta1 (IC50, >100 microM), and alpha5beta1 (IC50, >10 microM). Oral antiplatelet efficacy of DMP 802 was examined after single oral (0.05-0.20 mg/kg) and after repeated oral dosing at 0.05 mg/kg daily for 5 days in mongrel dogs. Dose-dependent antiplatelet efficacy with an extended duration of antiplatelet efficacy was demonstrated based on ex vivo inhibition of platelet aggregation induced by 100 microM ADP. DMP 802 has an oral bioavailability of 14.9% in dogs. In conclusion, the alpha sulfonamide isoxazoline analog, DMP 802, is a novel oral antiplatelet agent with high affinity, relatively slow dissociation rate and specificity for human platelet GPIIb/IIIa receptors.

Atrial fibrillation in the elderly: physicians' attitudes to anticoagulation.

The use of warfarin and aspirin for the primary prevention of stroke in elderly patients with atrial fibrillation (AF) is controversial. To establish current practice we circulated a questionnaire to 300 geriatricians (G) and 300 cardiologists (C). The response rates were 47% G and 51% C. Most physicians prescribed warfarin in AF associated with mitral stenosis (G vs C, 86% vs 89%, NS). Cardiologists were more likely to prescribe warfarin in AF associated with dilated cardiomyopathy (G vs C, 52% vs 86%, P < 0.01). A minority would prescribe warfarin in aortic valve disease and AF (G vs C, 37% vs 24%, P < 0.05) and lone AF (G vs C, 10% vs 26%, P < 0.01). Aspirin was favoured in aortic valve disease and lone AF. The cardiologists were less reluctant to use warfarin in the young and more likely to electrically cardiovert the young with chronic AF.

Antibacterials. synthesis and structure-activity studies of 3-aryl-2-oxooxazolidines. 4. Multiply-substituted aryl derivatives.

The synthesis and structure-activity relationship (SAR) studies of the effect of different polysubstitution patterns in the aromatic ring of 5-(acetamidomethyl)oxazolidinone antibacterials (I) on antibacterial activity are presented. Compounds I were prepared by the six-step synthesis described previously (Gregory, W. A.; et al. J. Med. Chem. [formula: see text] 1989, 32, 1673), electrophilic aromatic substitution reactions of 3-substituted compounds, and functional-group interchange reactions of 3,4-disubstituted compounds. Antibacterial evaluation of compounds I against Staphylococcus aureus and Enterococcus faecalis gave the following results. The 2,4- and 2,5-disubstituted derivatives have weak or no antibacterial activity. Antibacterial activities of 3,4-disubstituted compounds are comparable to those of the 4-monosubstituted analogues for small 3-substituents (smaller than Br), but decline rapidly for larger 3-substituents. 3,4-Annulated derivatives are comparable in activity to their open-chain analogues. 3,5-Disubstituted and 3,4,5- and 2,4,6-trisubstituted derivatives are devoid of antibacterial activity.