A collaborative hit-to-lead investigation leveraging medicinal chemistry expertise with high throughput library design, synthesis and purification capabilities.

High throughput screening (HTS) campaigns, where laboratory automation is used to expose biological targets to large numbers of materials from corporate compound collections, have become commonplace within the lead generation phase of pharmaceutical discovery. Advances in genomics and related fields have afforded a wealth of targets such that screening facilities at larger organizations routinely execute over 100 hit-finding campaigns per year. Often, 10(5) or 10(6) molecules will be tested within a campaign/cycle to locate a large number of actives requiring follow-up investigation. Due to resource constraints at every organization, traditional chemistry methods for validating hits and developing structure activity relationships (SAR) become untenable when challenged with hundreds of hits in multiple chemical families per target. To compound the issue, comparison and prioritization of hits versus multiple screens, or physical chemical property criteria, is made more complex by the informatics issues associated with handling large data sets. This article describes a collaborative research project designed to simultaneously leverage the medicinal chemistry and drug development expertise of the Novartis Institutes for Biomedical Research Inc. (NIBRI) and ArQule Inc.'s high throughput library design, synthesis and purification capabilities. The work processes developed by the team to efficiently design, prepare, purify, assess and prioritize multiple chemical classes that were identified during high throughput screening, cheminformatics and molecular modeling activities will be detailed.

Outbreak of carbapenem-resistant Acinetobacter baumannii in the intensive care unit: a multi-level strategic management approach.

An outbreak of carbapenem-resistant Acinetobacter baumannii (CRAb) occurred in an interdisciplinary intensive care unit, affecting 10 patients. Within hours of recognition of the spread of CRAb an intervention team was instituted for collection of available data, decision-making, communication and monitoring of all interventions performed, including cohorting, temporary stop of admissions, staff education, and enforcement of infection control measures. An area was defined for cohortation of patients colonized with CRAb, with a separate nursing team and a second set of mobile equipment. New transmissions were no longer observed after only four days into the institution of enhanced infection control measures.

Structural and conformational requirements for high-affinity binding to the SH2 domain of Grb2(1).

Following earlier work on cystine-bridged peptides, cyclic phosphopeptides containing nonreducible mimics of cystine were synthesized that show high affinity and specificity toward the Src homology (SH2) domain of the growth factor receptor-binding protein (Grb2). Replacement of the cystine in the cyclic heptapeptide cyclo(CYVNVPC) by D-alpha-acetylthialysine or D-alpha-lysine gave cyclo(YVNVP(D-alpha-acetyl-thiaK)) (22) and cyclo(YVNVP(D-alpha-acetyl-K)) (30), which showed improved binding 10-fold relative to that of the control peptide KPFYVNVEF (1). NMR spectroscopy and molecular modeling experiments indicate that a beta-turn conformation centered around YVNV is essential for high-affinity binding. X-ray structure analyses show that the linear peptide 1 and the cyclic compound 21 adopt a similar binding mode with a beta-turn conformation. Our data confirm the unique structural requirements of the ligand binding site of the SH2 domain of Grb2. Moreover, the potency of our cyclic lactams can be explained by the stabilization of the beta-turn conformation by three intramolecular hydrogen bonds (one mediated by an H2O molecule). These stable and easily accessible cyclic peptides can serve as templates for the evaluation of phosphotyrosine surrogates and further chemical elaboration.

Technetium-99m-HMPAO brain SPECT in patients with syndrome X.

Ninety-five patients with syndrome X were studied by brain single-photon emission computed tomographic examination; 72 (76%) had pathologic findings suggestive of cerebral perfusion abnormalities. These findings support the hypothesis of a vascular disorder not confined to cardiac vessels.

Binding of a Bolton-Hunter substituted homostatine analog to affinity-immobilized human renin.

The binding of a Bolton-Hunter reagent substituted homostatine analog, SDZ 213-776, to human renin was investigated at pH 6.5 and 7.4. At both pH values, SDZ 213-776 bound to human renin in a reversible and saturable manner. The binding characteristics conformed to a one-site binding model. The dissociation constant Kd, obtained at equilibrium, was four-fold lower at pH 6.5 that at pH 7.4 (0.94 nM vs 3.7 nM). Under non-equilibrium conditions, only the association kinetic constant k+1 was affected by pH. The results of the binding assay at pH 6.5 correlated well with those obtained in enzymatic assay at the same pH.

Epirubicin and ifosfamide in patients with refractory breast cancer and other metastatic solid tumours.

The combination of ifosfamide (IFO) and epirubicin (EPI) has been found to be an effective regimen in the treatment of metastatic tumours and shows remarkable activity in heavily pretreated breast cancer patients. A combination of EPI (35 mg/m2 on days 1 and 2) and IFO (1.8-2.5 g/m2 on days 1-5) was given to 58 patients with refractory breast cancer (n = 23), metastatic sarcomas (n = 15) and other solid tumours (n = 20). Due to extensive prior therapy, the IFO dose had to be adapted to the individual haematological situation. In all, 55 patients were evaluable; we observed 5 complete (CRs) and 16 partial responses (PRs). In addition, 18 patients experienced a minor response (MR) or no change (NC). The median duration of all responses was 6.7 months. Toxicity was generally mild and closely related to previous therapy.

Myocardial infarction as a complication of dobutamine stress echocardiography.

Only few cases of myocardial infarction complicating dobutamine stress echocardiography have been reported. We observed a 42-year-old woman in whom acute inferior wall infarction developed 10 minutes after discontinuation of dobutamine stress echocardiography with up to 20 micrograms/kg/min dobutamine. The right coronary artery, which had had a 50% stenosis in the prior angiography, showed proximal complete occlusion on the immediately performed recatheterization. Thrombolysis in myocardial infarction study flow grade 3 was rapidly accomplished by intracoronary thrombolysis with recombinant tissue type plasminogen activator. For recurrent unstable angina, the patient received coronary bypass grafting on the same day. The case shows that myocardial infarction not preceded by regional wall motion abnormalities is a possible complication of dobutamine stress echocardiography. Post-test monitoring even after negative tests is recommended.

[Fibrinolytic therapy of deep vein thrombosis]. / Lysetherapie bei tiefen Beinvenenthrombosen.

BACKGROUND: The most important complications of deep vein thrombosis are pulmonary embolism and postthrombotic syndrome. While the medicine of lethal pulmonary embolism is reduced to less than 2% by conventional anticoagulation, fibrinolytic therapy aims at a reduction of the greater than 50% incidence of postthrombotic syndrome. The optimal therapeutic regimen concerning risks and effect has not been established yet. RESULTS: A review of 26 studies involving ultrahigh-dose streptokinase (UHSK), urokinase (UK), and tissue-type plasminogen activator (rt-PA) shows the highest success rate for UHSK (45% complete and 40% parital patency), whereas there are lower rates for UK (25% and 40%) and low-dose locoregionally applied rt-PA (22% and 44%). The studies were not directly comparative, however. Published data concerning complications range from 1.7% mortality for UHSK to 0.9% for UK and 0.0% for rt-PA. Success criteria, however, are varying and not well defined. The influence of fibrinolytic therapy on the incidence of postthrombotic syndrome has not been established prospectively, but a reduction by 40 to 50% can be assumed. Calf vein thromboses are not indication for lytic therapy. In patients with iliacal vein thromboses there is an increased risk of pulmonary embolism using UHSK. CONCLUSIONS: UHSK can be regarded the standard concerning success rate in deep vein thromboses. DATA involving locoregional therapy with rt-PA are inconsistent and worse, but bleeding complications might be less frequent. Large prospective studies evaluating the impact on incidence and severity of the postthrombotic syndromes, which involve a controlled application of compression therapy are needed.

Mechanism of inactivation of chymotrypsin by 5-butyl-3H-1,3-oxazine-2,6-dione.

5-Butyl-3H-1,3-oxazine-2,6-dione (1) inactivates chymotrypsin. The extent of inactivation is dependent upon the concentration of 1. Upon dilution of the inactivated enzyme, catalytic activity is partially restored. Reactivation is a biphasic process. An initial relatively rapid phase (k = 1.8 X 10(-2) min), whose amplitude is dependent upon the extent of dilution, is observed. Maximally, 60-65% of the catalytic activity can be recovered. The rapid phase is followed by a slow phase (k approximately 1 X 10(-3) min-1). With 1 labeled with 14C at C-2, it was shown that two forms of inactive enzyme are formed, E.1 and E.1'. 14C label is retained in E.1 but is no longer present in E.1'. Presumably, C-2 is lost as CO2. The following reaction sequence is proposed for the inactivation of chymotrypsin: E + 1 in equilibrium E.1 CO2----E.1'----E + 1''. The probable structures of E.1, E . 1', and 1'' are shown in Scheme I in the text.

[Increased rate of sister chromatid exchange following therapy of acute lymphoblastic leukemias and non-Hodgkin lymphomas in childhood]. / Erhöhte Schwesterchromatidenaustauschrate nach Therapie kindlicher akuter lymphoblastischer Leukämien und Non-Hodgkin-Lymphome.

Sister chromatid exchanges rates (SCE) were studied in peripheral blood lymphocytes of 10 patients with acute lymphoblastic leukaemia (ALL) or leukaemic transformed non-Hodgkin-lymphomas (NHL) and in lymphocytes of 10 healthy juvenile donors (control). Following treatment the patient group has been in continuous complete remission for 11 months on the average. In the number of SCE's significant differences were found: 10,90/metaphases in the patients versus 7,56/metaphases in the controls. These results significantly show a long time influence of the treatment on the SCE rates, possibly inducing chromosome aberrations.

[Alpha 2-interferon in kidney cancer. Experiences with 6 patients]. / Alpha 2-Interferon beim Nierenkarzinom: Erfahrungen an sechs Patienten.

We report on 6 male patients with advanced renal cell carcinoma without prior chemotherapy. They were treated by recombinant alpha 2-interferon in a toxicity limited dosage. The maximal tolerated dose was 3 x 5 x 10(6) U/wk. to 3 x 20 x 10(6) U/wk., limited by flu-like symptoms in 5 cases, by thrombopenia in 1. We observed a response in 3 cases (2 partial remissions, 1 mixed response) lasting for 10, 11 and 13 months, respectively. This comparatively good result may be due to patient characteristics (little pretreatment, pulmonary metastasis, good performance status) as well as to a medium dosage. Occurrence of response after termination of interferon therapy in two cases are of particular interest.

[Acute pancreatitis caused by atrial fibrillation?]. / Vorhofflimmern als mögliche Ursache für eine akute Pankreatitis?

HISTORY: We report three male patients who had atrial fibrillation with a rapid and irregular ventricular rate, aged 60, 69 and 70 years, respectively, in whom development of acute pancreatitis occurred simultaneously with other ischaemic events. INVESTIGATIONS: One of these patients simultaneously suffered from a transient ischaemic attack (TIA), another developed a stroke and an infarction of the spleen, while the third one had a splenic infarction and an embolism in the region of the mesenteric arteries. Two patients had paroxysmal atrial fibrillation, while the third suffered from ischemic cardiomyopathy with chronic atrial fibrillation. DIAGNOSIS AND TREATMENT: Oedematous pancreatitis occurred in one patient while, in the two others, the diagnosis of severe necrotizing pancreatitis was made. CONCLUSION: Atrial fibrillation is the most common sustained arrhythmia encountered in clinical practice and a recognized risk factor for the development of peripheral embolism, which often takes the form of an ischaemic stroke. It is a major cause of stroke, especially in the elderly. Because of the simultaneous occurrence of thromboembolic events in all three patients, an ischaemic cause for the acute pancreatitis can be assumed with a high degree of probability. This is one of the first reports of acute ischaemic pancreatitis probably caused by microembolization secondary to atrial fibrillation. Because of the relatively frequent occurrence of atrial fibrillation, this factor deserves increased attention in the differential diagnosis of supposedly idiopathic pancreatitis.

Hypersensitivity reactions to carboplatin. Report of two patients, review of the literature, and discussion of diagnostic procedures and management.

BACKGROUND: Hypersensitivity reactions are rare but sometimes life-threatening complications of cytostatic combinations containing platinum compounds. Only approximately 40 instances of such hypersensitivity have been reported in association with carboplatin treatment. However, the symptoms probably often are misinterpreted. METHOD: Signs and symptoms of two patients with severe hypersensitivity reactions to carboplatin are presented. Intracutaneous tests with carboplatin were performed in these two patients and in five control patients receiving carboplatin therapy without unexpected side effects. RESULTS: Both patients had received several cycles of a carboplatin-containing combination chemotherapy. In both patients, hypersensitivity reactions became manifest for the first time after cumulative doses of 3900 and 5400 mg, respectively. Symptoms included dyspnea, tachycardia, angina pectoris, hypotension, diarrhea, edema, and rash. In both patients, a positive urticarial reaction to intracutaneous carboplatin (diluted 1:10 with normal saline) was observed, whereas five control patients undergoing carboplatin therapy without adverse reaction had negative test results. There were no signs of delayed hypersensitivity. Serum immunoglobulin E levels were normal. Symptoms were ameliorated but not suppressed when one patient was reexposed after premedication with corticosteroids and histamine antagonists. Both patients tolerated high doses of cisplatin without allergic reactions. CONCLUSIONS: Although they are rare, hypersensitivity reactions can be serious complications of carboplatin therapy. Simple intracutaneous tests might help to establish the diagnosis to avoid dangerous reexposures. Although the pathogenetic mechanisms are not fully understood, the clinical and experimental findings suggest an anaphylactic type of hypersensitivity, perhaps aggravated to some extent by nonspecific histamine liberation. There seems to be no general cross-reactivity to cisplatin.