Development and Comprehensive Benchmark of a High-Quality AMBER-Consistent Small Molecule Force Field with Broad Chemical Space Coverage for Molecular Modeling and Free Energy Calculation

Biomolecular simulations have become an essential tool in contemporary drug discovery, and molecular mechanics force fields (FFs) constitute its cornerstone. Developing a high quality and broad coverage general FF is a significant undertaking that requires substantial expert knowledge and computing resources, which is beyond the scope of general practitioners. Existing FFs originate from only a limited number of groups and organizations, and they either suffer from limited numbers of training sets, lower than desired quality because of oversimplified representations, or are costly for the molecular modeling community to access. To address these issues, in this work, we developed an AMBER-consistent small molecule FF with extensive chemical space coverage, and we provide Open Access parameters for the entire modeling community. To validate our FF, we carried out benchmarks of quantum mechanics (QM)/molecular mechanics conformer comparison and free energy perturbation calculations on several benchmark data sets. Our FF achieves a higher level of performance at reproducing QM energies and geometries than two popular open-source FFs, OpenFF2 and GAFF2. In relative binding free energy calculations for 31 protein-ligand data sets, comprising 1079 pairs of ligands, the new FF achieves an overall root-mean-square error of 1.19 kcal/mol for ΔΔG and 0.92 kcal/mol for ΔG on a subset of 463 ligands without bespoke fitting to the data sets. The results are on par with those of the leading commercial series of OPLS FFs.

1,2-Difunctionalized bicyclo[1.1.1]pentanes: Long-sought-after mimetics for ortho/meta-substituted arenes

The development of a versatile platform for the synthesis of 1,2-difunctionalized bicyclo[1.1.1]pentanes to potentially mimic ortho/meta-substituted arenes is described. The syntheses of useful building blocks bearing alcohol, amine, and carboxylic acid functional handles have been achieved from a simple common intermediate. Several ortho- and meta-substituted benzene analogs, as well as simple molecular matched pairs, have also been prepared using this platform. The results of in-depth ADME (absorption, distribution, metabolism, and excretion) investigations of these systems are presented, as well as computational studies which validate the ortho- or meta-character of these bioisosteres.

Characterization of Specific N-α-Acetyltransferase 50 (Naa50) Inhibitors Identified Using a DNA Encoded Library

Two novel compounds were identified as Naa50 binders/inhibitors using DNA-encoded technology screening. Biophysical and biochemical data as well as cocrystal structures were obtained for both compounds (3a and 4a) to understand their mechanism of action. These data were also used to rationalize the binding affinity differences observed between the two compounds and a MLGP peptide-containing substrate. Cellular target engagement experiments further confirm the Naa50 binding of 4a and demonstrate its selectivity toward related enzymes (Naa10 and Naa60). Additional analogs of inhibitor 4a were also evaluated to study the binding mode observed in the cocrystal structures.

Sequential ALK Inhibitors Can Select for Lorlatinib-Resistant Compound ALK Mutations in ALK-Positive Lung Cancer

The cornerstone of treatment for advanced ALK-positive lung cancer is sequential therapy with increasingly potent and selective ALK inhibitors. The third-generation ALK inhibitor lorlatinib has demonstrated clinical activity in patients who failed previous ALK inhibitors. To define the spectrum of ALK mutations that confer lorlatinib resistance, we performed accelerated mutagenesis screening of Ba/F3 cells expressing EML4-ALK. Under comparable conditions, N-ethyl-N-nitrosourea (ENU) mutagenesis generated numerous crizotinib-resistant but no lorlatinib-resistant clones harboring single ALK mutations. In similar screens with EML4-ALK containing single ALK resistance mutations, numerous lorlatinib-resistant clones emerged harboring compound ALK mutations. To determine the clinical relevance of these mutations, we analyzed repeat biopsies from lorlatinib-resistant patients. Seven of 20 samples (35%) harbored compound ALK mutations, including two identified in the ENU screen. Whole-exome sequencing in three cases confirmed the stepwise accumulation of ALK mutations during sequential treatment. These results suggest that sequential ALK inhibitors can foster the emergence of compound ALK mutations, identification of which is critical to informing drug design and developing effective therapeutic strategies.Significance: Treatment with sequential first-, second-, and third-generation ALK inhibitors can select for compound ALK mutations that confer high-level resistance to ALK-targeted therapies. A more efficacious long-term strategy may be up-front treatment with a third-generation ALK inhibitor to prevent the emergence of on-target resistance. Cancer Discov; 8(6); 714-29. ©2018 AACR.This article is highlighted in the In This Issue feature, p. 663.

Resensitization to Crizotinib by the Lorlatinib ALK Resistance Mutation L1198F

In a patient who had metastatic anaplastic lymphoma kinase (ALK)-rearranged lung cancer, resistance to crizotinib developed because of a mutation in the ALK kinase domain. This mutation is predicted to result in a substitution of cysteine by tyrosine at amino acid residue 1156 (C1156Y). Her tumor did not respond to a second-generation ALK inhibitor, but it did respond to lorlatinib (PF-06463922), a third-generation inhibitor. When her tumor relapsed, sequencing of the resistant tumor revealed an ALK L1198F mutation in addition to the C1156Y mutation. The L1198F substitution confers resistance to lorlatinib through steric interference with drug binding. However, L1198F paradoxically enhances binding to crizotinib, negating the effect of C1156Y and resensitizing resistant cancers to crizotinib. The patient received crizotinib again, and her cancer-related symptoms and liver failure resolved. (Funded by Pfizer and others; ClinicalTrials.gov number, NCT01970865.).

Abstract PR10: Is CNS availability for oncology a no-brainer? Discovery of PF-06463922, a novel small molecule inhibitor of ALK/ROS1 with preclinical brain availability and broad spectrum potency against ALK-resistant mutations

Oncogenic fusions of anaplastic lymphoma kinase (ALK) define a subset of human lung adenocarcinoma. The 1st generation ALK inhibitor crizotinib demonstrated impressive clinical benefit in ALK-fusion positive lung cancers and was approved by the FDA for the treatment of ALK-fusion positive NSCLC in 2011. However, as seen with most kinase inhibitors, patients treated with crizotinib eventually develop resistance to therapy. Acquired ALK kinase domain mutations and disease progression in the central nervous system (CNS) are reported as main contributors to patient relapse after ALK inhibitor therapy. Preclinically, crizotinib lacks significant brain penetration and does not potently inhibit activity of ALK kinase domain mutants, so a drug discovery program was initiated aimed to develop a second generation ALK inhibitor that is more potent than existing ALK inhibitors, capable of inhibiting the resistant ALK mutants and penetrating the blood-brain-barrier. These objectives present a considerable challenge in kinase inhibitor chemical space. Here we report that PF-06463922, a novel small molecule ATP-competitive inhibitor of ALK/ROS1, showed exquisite potencies against non-mutant ALK (Ki <0.2 nM; cell IC50 ∼2 nM) and ROS1 kinase (Ki <0.005 nM; cell IC50 ∼0.2 nM), and demonstrated low nanomolar inhibitory activity against a panel of ALK kinase domain mutants representing all of the patient crizotinib resistant mutations reported to date. The more commonly reported L1196M gatekeeper mutant shows significant sensitivity to PF-06463922 (Ki 0.7 nM; cell IC50 16 nM). PF-06463922 is also very selective, and showed >100 fold kinase selectivity against 95% of the kinases tested in a 207 recombinant kinase panel. Specific design considerations were developed leading to novel ATP-competitive kinase inhibitors with desired low efflux in cell lines over-expressing p-glycoprotein and breast cancer resistance protein, providing excellent blood-brain-barrier and cell penetration properties. Efforts to optimize ligand efficiency and lipophilic efficiency leveraging structure based drug design techniques led to ligands with overlapping broad spectrum potency and low efflux. Single and repeat dose preclinical rat in vivo studies of PF-06463922 demonstrated excellent oral bioavailability and CNS availability with free brain exposure approximately 30% of free plasma levels. In addition, CNS-directed safety studies showed no adverse events at predicted efficacious concentrations. It is anticipated that PF-06463922 with its potent activities on non-mutant ALK, ALK kinase domain mutations and CNS metastases would provide great promise for patients with ALK and ROS1 positive cancers.

Citation Information: Mol Cancer Ther 2013;12(11 Suppl):PR10.

Citation Format: Ted W. Johnson, Simon Bailey, Benjamin J. Burke, Michael R. Collins, J. Jean Cui, Judy Deal, Ya-Li Deng, Martin P. Edwards, Mingying He, Jacqui Hoffman, Robert L. Hoffman, Qinhua Huang, Robert S. Kania, Phuong Le, Michele McTigue, Cynthia L. Palmer, Paul F. Richardson, Neal W. Sach, Graham L. Smith, Lars Engstrom, Wenyue Hu, Hieu Lam, Justine L. Lam, Tod Smeal, Helen Y. Zou. Is CNS availability for oncology a no-brainer? Discovery of PF-06463922, a novel small molecule inhibitor of ALK/ROS1 with preclinical brain availability and broad spectrum potency against ALK-resistant mutations. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr PR10.

Discovery of novel, potent, and selective inhibitors of 3-phosphoinositide-dependent kinase (PDK1)

Analogues substituted with various amines at the 6-position of the pyrazine ring on (4-amino-7-isopropyl-7H-pyrrolo[2,3-d]pyrimidin-5-yl)pyrazin-2-ylmethanone were discovered as potent and selective inhibitors of PDK1 with potential as anticancer agents. An early lead with 2-pyridine-3-ylethylamine as the pyrazine substituent showed moderate potency and selectivity. Structure-based drug design led to improved potency and selectivity against PI3Kα through a combination of cyclizing the ethylene spacer into a saturated, five-membered ring and substituting on the 4-position of the aryl ring with a fluorine. ADME properties were improved by lowering the lipophilicity with heteroatom replacements in the saturated, five-membered ring. The optimized analogues have a PDK1 Ki of 1 nM and >100-fold selectivity against PI3K/AKT-pathway kinases. The cellular potency of these analogues was assessed by the inhibition of AKT phosphorylation (T308) and by their antiproliferation activity against a number of tumor cell lines.

Quantifying and predicting the promiscuity and isoform specificity of small-molecule cytochrome P450 inhibitors

Drug promiscuity (i.e., inhibition of multiple enzymes by a single compound) is increasingly recognized as an important pharmacological consideration in the drug development process. However, systematic studies of functional or physicochemical characteristics that correlate with drug promiscuity are handicapped by the lack of a good way of quantifying promiscuity. In this article, we present a new entropy-based index of drug promiscuity. We apply this index to two high-throughput data sets describing inhibition of cytochrome P450 isoforms by small-molecule drugs and drug candidates, and we demonstrate how drug promiscuity or specificity can be quantified. For these drug-metabolizing enzymes, we find that there is essentially no correlation between a drug's potency and specificity. We also present an index to quantify the susceptibilities of different enzymes to inhibition by diverse substrates. Finally, we use partial least-squares regression to successfully predict isoform specificity and promiscuity of small molecules, using a set of fingerprint-based descriptors.

Skeletal and Cardiac Muscle Defects in a Murine Model of Emery-Dreifuss Muscular Dystrophy

Previous histological findings, physiological data, and behavioral observations on the A-type lamin knockout mouse (Lmna(-/-)) suggest that important aspects of this model resemble the human Emery-Dreifuss muscular dystrophy (EDMD) phenotype. The main goal of our experiments was to study skeletal and cardiac muscle function in this murine model to obtain the semiquantitative data needed for more detailed comparisons with human EDMD defects. Measurements of the mechanical properties of preparations from two different skeletal muscle groups, the soleus and the diaphragm, were made in vitro. In addition, records of the electrocardiogram, and measurements of heart rate variability were obtained; and phasic contractions (unloaded shortening) of enzymatically isolated ventricular myocytes were monitored. Soleus muscles from Lmna(-/-) mice produced less force and work than control preparations. In contrast, force and work production in strips of diaphragm were not changed significantly. Lead II electrocardiograms from conscious, restrained Lmna(-/-) mice revealed slightly decreased heart rates, with significant prolongations of PQ, QRS, and 'QT' intervals compared with those from control recordings. These ECG changes resemble some aspects of the ECG records from humans with EDMD; however, the cardiac phenotype in this Lmna(-/-) mouse model appears to be less well-defined/developed. Ventricular myocytes isolated from Lmna(-/-) mice exhibited impaired contractile responses, particularly when superfused with the beta-adrenergic agonist, isoproterenol (1 microM). This deficit was more pronounced in myocytes isolated from the left ventricle(s) than in myocytes from the right ventricle(s). In summary, tissues from the Lmna(-/-) mouse exhibit a number of skeletal and cardiac muscle deficiencies, some of which are similar to those which have been reported in studies of human EDMD.

The retinol-binding protein system: a potential paradigm for steroid-binding globulins?

Retinol (vitamin A) is an example of a small molecule that is essential for higher organisms; its utilisation has been involved in the evolution of a number of proteins. In mammalian species, retinol is obtained from the diet and controls the release of its binding protein from hepatocytes into the blood stream. Subsequent influx into cells under normal situations usually involves a specific membrane-bound receptor for retinol-binding protein, which facilitates the uptake of retinol alone or bound to its carrier. This specific receptor has not yet been identified, but a receptor for a related lipocalin has been cloned. It represents a relatively new family, and there are a number of related genes in various eukaryotic genomes, suggesting that the system is very widespread in multicellular organisms. Its significance has been highlighted recently by the suggestion that retinol-binding protein, through its receptor, may play a major role in type 2 diabetes, perhaps the greatest scourge of modern society. This system may provide a new paradigm in mammalian biology, another example of which may exist in the processes responsible for steroid handling. This review outlines the characteristics of retinol utilisation in mammalian species, focusing primarily on the uptake system.

Electrophoretically mediated microanalysis of beta-galactosidase on microchips

Electrophoretically mediated microanalysis (EMMA) is a method of accomplishing chemical analyses, typically in an open-tubular capillary, due to the difference in the electrophoretic mobility between the particular reagents. This work reports on combining this technique onto microfabricated systems. Two methods of this technique were applied, constant potential and zero potential EMMA onto chips. A dosage response curve was run using this constant potential mode that resulted in a linear response over three orders of substrate concentration magnitude. The chemical system used here is beta-galactosidase (beta-Gal) as the enzyme and fluorescein mono-beta-D-galactopyranoside (FMG) as the substrate. The zero potential mode was used to amplify product turnover using various incubation times. Using this technique and a 10 min incubation, approximately 40000 enzyme molecules could be detected. The zero potential mode is also used in conjunction with an internal standard to show how one can quantitate using this method. The power and ease of utility of this technique is described.

A Picoliter-Volume Mixer for Microfluidic Analytical Systems

Mixing confluent liquid streams is an important, but difficult operation in microfluidic systems. This paper reports the construction and characterization of a 100-pL mixer for liquids transported by electroosmotic flow. Mixing was achieved in a microfabricated device with multiple intersecting channels of varying lengths and a bimodal width distribution. All channels running parallel to the direction of flow were 5 microm in width whereas larger 27-microm-width channels ran back and forth through the parallel channel network at a 45 degrees angle. The channel network composing the mixer was approximately 10 microm deep. It was observed that little mixing of the confluent solvent streams occurred in the 100-microm-wide, 300-microm-long mixer inlet channel where mixing would be achieved almost exclusively by diffusion. In contrast, after passage through the channel network in the approximately 200-microm-length static mixer bed, mixing was complete as determined by confocal microscopy and CCD detection. Theoretical simulations were also performed in an attempt to describe the extent of mixing in microfabricated systems.

Electrophoretically mediated microanalysis of leucine aminopeptidase using two-photon excited fluorescence detection on a microchip

Two-photon excited fluorescence detection was performed on a microfabricated electrophoresis chip. A calibration curve of the fluorescent tag beta-naphthylamine was performed, resulting in a sensitivity of 2.5 x 10(9) counts M(-1) corresponding to a detection limit of 60 nM. Additionally, leucine aminopeptidase was assayed on the chip using electrophoretically mediated microanalysis. The differential electroosmotic mobilities of the enzyme and substrate, L-leucine beta-naphthylamide, allowed for efficient mixing in an open channel, resulting in the detection of a 30 nM enzyme solution under constant potential. A zero potential incubation for 1 min yielded a calculated detection limit of 4 nM enzyme.

Structure-based design, synthesis, and biological evaluation of irreversible human rhinovirus 3C protease inhibitors. 4. Incorporation of P1 lactam moieties as L-glutamine replacements

The structure-based design, chemical synthesis, and biological evaluation of various human rhinovirus (HRV) 3C protease (3CP) inhibitors which incorporate P1 lactam moieties in lieu of an L-glutamine residue are described. These compounds are comprised of a tripeptidyl or peptidomimetic binding determinant and an ethyl propenoate Michael acceptor moiety which forms an irreversible covalent adduct with the active site cysteine residue of the 3C enzyme. The P1-lactam-containing inhibitors display significantly increased 3CP inhibition activity along with improved antirhinoviral properties relative to corresponding L-glutamine-derived molecules. In addition, several lactam-containing compounds exhibit excellent selectivity for HRV 3CP over several other serine and cysteine proteases and are not appreciably degraded by a variety of biological agents. One of the most potent inhibitors (AG7088, mean antirhinoviral EC90 approximately 0.10 microM, n = 46 serotypes) is shown to warrant additional preclinical development to explore its potential for use as an antirhinoviral agent.

Ureteral jets in normal second- and third-trimester pregnancy

PURPOSE

We wished to assess whether urodynamic changes accompanying normal pregnancy altered the pattern of ureteral jets, complicating detection of pathologic obstruction.

METHODS

Ureteral jets were observed with color Doppler sonography for 5 minutes in 26 women in the second or third trimester of pregnancy and in 6 non-pregnant controls (3 men and 3 women).

RESULTS

A mean of 5.5 jets/minute were detected in the pregnant subjects, and the mean difference in frequency of jets between the right and left sides was 42%. Corresponding results for controls were 7.6 jets/minute and 11%, respectively. The 2 groups were significantly different with respect to jet symmetry (p < 0.02). Unilateral absence of jets was noted in 4 pregnant women but in no controls.

CONCLUSIONS

Because of variation in ureteral jet bilaterality and symmetry during the later stages of pregnancy, caution is recommended in the use of the technique to diagnose obstructive urolithiasis in this population.

Evaluation of palpable breast masses with color Doppler sonography and gray scale imaging

Excisional biopsy is the standard method of distinguishing benign from malignant masses of the breast. However, alternative, less invasive methods of diagnosis are needed to reduce the number of unnecessary biopsies, allay anxiety of the patient, and control costs. In this study, we evaluated breast masses in a series of patients using color Doppler sonography and gray scale ultrasonographic features. In all cases, the pathologic diagnosis of the breast mass was subsequently established by excisional biopsy. The accuracy of gray scale sonography exceeded that of color Doppler sonography at a significance level of P < 0.005.

The Ranawat Award. Sulcus morphology of the distal femur

Traditional images of the distal femur place the intercondylar groove midway between the condyles. The location of the sulcus of the intercondylar groove in a large Sudanese skeletal population was verified using a custom stereotactic device. The results of this study show that the femoral sulcus is lateral to the midplane between the 2 femoral condyles. This study also shows that the configuration of the sulcus is linear and is oriented between the traditional anatomic and mechanical axes of the femur.

A generalized formalism of three-dimensional quantitative structure-property relationship analysis for flexible molecules using tensor representation

A general formalism, based upon tensor representation of multidimensional data blocks, is presented to express relationships between dependent properties and independent molecular feature measures. The solutions to these data set problems are three-dimensional quantitative structure-property relationships, 3D-QSPRs. The molecular features are partitioned into the intrinsic molecular shape tensor, the molecular field tensor, a nonshape/field feature tensor, and an experimental feature tensor. The intrinsic molecular shape tensor contains information on the shape of a molecule within the contact surface while the molecular field tensor contains information outside of the contact surface. Molecular features not directly related to molecular shape are put into the nonshape/field tensor. Experimental measures not being used as dependent variables can be considered as independent molecular features in the experimental feature tensor. The 3D-QSPR is realized by constructing the transformation tensor which optimizes the statistical significance between the dependent and independent variables. Use of partial least squares (PLS) regression permits the unfolding of the composite feature tensor and the identification of the optimum transformation tensor. It is pointed out that a variety of fragment, whole-molecule, two-dimensional, and/or three-dimensional features can be placed into a nonshape/field tensor.

Construction of a molecular shape analysis-three-dimensional quantitative structure-analysis relationship for an analog series of pyridobenzodiazepinone inhibitors of muscarinic 2 and 3 receptors

A generalized three-dimensional (3D) quantitative structure-property relationship (QSPR) formalism, based upon molecular shape analysis (MSA), has been applied to an analog series of pyridobenzodiazepinone inhibitors of muscarinic 2 (M2) and 3 (M3) receptors. The fundamental goal of this application is to establish MSA-3D-QSARs (P = A = inhibition activity) that are based upon identifying the active conformations of these flexible analogs. The repetitive use of partial least squares (PLS) analysis permits the construction of the MSA-3D-QSARs. In addition to molecular shape, the identification of the properties of a lipophilic binding site and specific nonallowed steric receptor sites govern the MSA-3D-QSARs. The M2 and M3 QSARs suggest receptor subtype specificity might be realized by targeting upon a specific nonallowed steric receptor site. One conformation, common to both M2 and M3 receptors, emerges as dominant in the optimum MSA-3D-QSARs. However, other similar conformations are also found to yield meaningful MSA-3D-QSARs.

Stereotaxic core breast biopsy: value in providing tissue for flow cytometric analysis

OBJECTIVE

Stereotaxic core biopsy provides intact samples of breast tissue for accurate histologic analysis. We conducted a study to determine if prognostic data could also be successfully derived from such core samples and how the data correlate with surgical biopsy.

MATERIALS AND METHODS

Both core and surgical breast biopsies from 135 patients were processed under a uniform flow cytometry protocol. Samples were coded and then randomly processed at an outside flow cytometer and interpreted by an independent pathologist; the code was broken and patients' results correlated only after all samples were completely analyzed.

RESULTS

Core breast biopsy provides intact tissue that can be successfully processed by a flow cytometer, even after being embedded in paraffin for initial histologic analysis. Larger cores (14 gauge) had fewer insufficient samples, as recorded on ploidy histograms. Although ploidy may reflect the underlying aggressiveness of a lesion and assist in evaluating breast cancer, surgical-pathologic correlation with stereotaxic biopsy indicated, as has been confirmed in other studies, considerable overlap of different ploidy types between benign and malignant conditions. There was no correlation between mammographic presentation and ploidy or S-phase fractions.

CONCLUSION

Stereotaxic large-core biopsy can enable accurate histologic diagnosis of breast disease and furnish sufficient tissue for flow cytometric measurements of ploidy and S-phase fractions, even at an interval following paraffinization. Such prognostic information aids in planning of adjuvant therapy, allows flexibility should surgery fail to provide enough tissue for DNA study, and helps radiologists further market stereotaxic biopsy to clinicians.

Human aminoacylase-1. Cloning, sequence, and expression analysis of a chromosome 3p21 gene inactivated in small cell lung cancer

Human aminoacylase-1 (N-acyl-L-amino-acid amidohydrolase, EC 3.5.1.14; ACY1) is a homodimeric zinc-binding enzyme that catalyzes the hydrolysis of N alpha-acylated amino acids. ACY1 has been assigned to chromosome 3p21.1, a region reduced to homozygosity in small cell lung cancer (SCLC), and has been reported to exhibit reduced or absent expression in SCLC cell lines and tumors. Two human cDNA libraries and one human genomic DNA library were screened with a previously isolated partial ACY1 cDNA to isolate a full-length transcript. Sequence analysis of clones from each of these libraries resulted in an ACY1 cDNA of 1438 base pairs with an open reading frame of 1224-base pairs coding for a putative protein of 408 amino acids with a predicted molecular mass of 45,882 Da. Sequence analysis revealed no homologies to previously reported cDNA or protein sequences and establishes ACY1 as the first member of a new family of zinc-binding enzymes to be so characterized. The subcellular location of ACY1 has been established as cytosolic by flow cytometry. Southern and northern analyses of ACY1 in SCLC cell lines failed to demonstrate any gross abnormalities of the ACY1 structural gene or instances of absent or aberrantly sized mRNA, respectively.

Segmental stenosis of the renal artery: pattern recognition of tardus and parvus abnormalities with duplex sonography

Segmental renal artery branches within the renal sinus were prospectively evaluated with color Doppler imaging and pulsed-Doppler spectral analysis in 56 patients before angiography. Waveforms were evaluated for the tardus and parvus abnormalities of prolonged acceleration time, diminished acceleration index, and loss of the normal early systolic compliance peak/reflective-wave complex (ESP). Findings obtained with these parameters were compared with the subsequent findings on angiograms to ascertain their efficacy in detection of hemodynamically significant (greater than or equal to 60%) renal arterial stenosis (RAS), which was present in 32 kidneys in 26 patients. Simple pattern-recognition analysis of ESP proved to be the best of the three parameters. Loss of ESP enabled identification of RAS with 95% sensitivity, 97% specificity, a 92% positive predictive value, a 98% negative predictive value, a 96% overall accuracy. On the basis of the high technical success rate, high sensitivity and specificity, and short examination time, waveform analysis for detection of tardus-parvus abnormalities, especially loss of ESP, of the segmental artery is recommended as an alternative to direct examination of the main renal arteries for evaluation of RAS.

MR imaging of symptomatic peripheral vascular malformations

We performed a retrospective study of symptomatic peripheral vascular malformations to determine if MR imaging can be used to distinguish slow-flow venous malformations from high-flow arteriovenous malformations and arteriovenous fistulas. Twenty-seven MR examinations in 25 patients with malformations outside the CNS were reviewed. Sixteen venous malformations, nine arteriovenous malformations, and two arteriovenous fistulas were included. In all cases, the MR findings were correlated with the results of angiography. The distinction between slow-flow venous malformations and high-flow arteriovenous malformations and arteriovenous fistulas was made primarily on T2-weighted MR images, which showed high signal intensity in venous malformations and flow voids in high-flow lesions. In addition to the previously described MR features of venous malformations (serpentine pattern with septations, associated muscle atrophy, and typical T1 and T2 signal intensities), several new MR features were apparent. Venous malformations had a propensity for multifocal involvement (37%), orientation along the long axis of extremities or affected muscles (78%), and adherence to neurovascular distributions (64%). Prominent subcutaneous fat was commonly seen adjacent to the malformation. MR images of arteriovenous malformations and arteriovenous fistulas also commonly showed muscle atrophy and subcutaneous fatty prominence. Our results show that slow-flow venous malformations can be distinguished from high-flow arteriovenous malformations and fistulas on the basis of spin-echo MR signal characteristics. The associated imaging characteristics help in the differential diagnosis in problematic cases.

Body space measurements in the hyponatraemia of carcinoma of the bronchus: evidence for the chronic 'sick cell' syndrome?

Body space measurements using simultaneous multiple isotope dilution techniques were made in both hyponatraemic and normonatraemic patients with carcinoma of the bronchus and wasting, and compared with those in a group of normal volunteers. Both groups of patients showed osmolal loss from cells. The significance of these findings in relation to the development of hyponatraemia is discussed.

Nonpalpable breast lesions: stereotactic automated large-core biopsies

One hundred two patients with mammographically suspicious, nonpalpable lesions underwent stereotactic breast biopsy with a biopsy gun and an automated 14-gauge cutting needle. After biopsy, a localization wire was placed and surgical biopsy performed. There was agreement of the histologic results from the gun biopsy and the surgical biopsy specimens in 98 cases (96%), including 22 of 23 carcinomas (96%) (kappa = 0.936). The gun biopsy yielded findings that led to the correct diagnosis in two cases involving lesions that were missed at surgical biopsy; two lesions found at surgery were missed at gun biopsy. The results of this study suggest that the use of 14-gauge needles improves agreement between surgical and needle core biopsy findings and that stereotactic biopsy with an automated needle and gun can be an acceptable alternative to surgical biopsy in women with mammographically suspicious breast lesions.

Stereotactic breast biopsy with a biopsy gun

One hundred three patients underwent stereotactic breast biopsy with an 18-, 16-, or 14-gauge cutting needle and a biopsy gun. After biopsy, a localization wire was placed and surgical biopsy performed. There was agreement of the histologic results in 89 cases (87%) including 14 of 16 cancers (87%) (kappa = 0.806). The gun biopsy yielded the correct diagnosis in four cases involving a lesion (including one cancer) that was missed at the surgical biopsy. Nine cases in which the lesion was missed at gun biopsy can be related to insufficient needle size, the greater difficulty in using one of the two stereotactic devices, and early inexperience with the technique. A 14-gauge needle was used in the last 29 biopsies, the results of which agreed with the surgical pathologic findings in 28 cases (97%). With greater experience, stereotactic-guided large-gauge automated percutaneous biopsy may prove to be an acceptable alternative to surgical biopsy in women with breast masses suspected at mammography.

1-(substituted-benzyl)imidazole-2(3H)-thione inhibitors of dopamine beta-hydroxylase

Molecular shape and quantitative structure-activity relationship (QSAR) analyses of 52 1-(substituted-benzyl)-imidazole-2(3H)-thione inhibitors of dopamine beta-hydroxylase were carried out. QSARs were developed for sets of 45 and sets of 47 analogues. Molecular shape, as represented by common overlap steric volume and the composite charge density on carbons 3, 4, and 5 of the substituted-benzyl ring are the major inhibition-potency descriptors. Five of the 52 compounds were eliminated prior to analyses on the basis of difficulties in characterizing shape and charge state. Two compounds were outliers. The active conformation deduced in the analyses is a low-energy conformer for both active and inactive inhibitors. This suggests that the intrinsic shape of the molecule due to the selection of X is more important than torsion-angle selection for the bonds between the two rings. The QSARs found in this study have only general similarities to one put forth by Kruse et al. using linear free energy descriptors.

Improved diabetic control in insulin-dependent diabetics treated with insulin and glibenclamide

A randomized double blind trial of insulin and glibenclamide treatment vs insulin and placebo was carried out in 20 insulin-dependent diabetics. Nine patients were C-peptide secretors and all increased their C-peptide output during a 50 g OGTT at the end of the insulin and glibenclamide treatment period by a mean of 47%. At the same time their mean daily blood glucose fell from 8.4 +/- 1.7 to 7.4 +/- 1.5 mmol/l and their HbA1 from 8.1 +/- 0.5 to 7.5 +/- 0.9% (mean +/- SD). There was no change in any of the measurements of diabetic control in C-peptide non-secretors and no evidence for any extra-pancreatic effects of glibenclamide in this group of patients. Combined insulin and glibenclamide treatment may produce a useful improvement of diabetic control in insulin-dependent diabetics who still secrete some endogenous insulin, although further studies are required.

The radiation dose to man following the intravenous injection of radiosulphate (Na2(35)SO4)

An estimation of the radiation dose to mans' testes, the critical organ, for radiosulphate (Na2(35)SO4) has been made by a combination of studies on rats and human volunteers. The radiation dose to rats testes and the rate of disappearance of radiosulphate from the blood and urine of humans have been increased. The calculated radiation dose of 7.7 muGy/MBq to mans' testes is lower than previously reported.

Heparin-associated priapism

A patient who developed priapism 7 hr after stopping an intravenous heparin infusion is described. Abnormal spontaneous platelet aggregation was demonstrated whilst on heparin treatment and is thought to play a role in the aetiology of heparin induced priapism.

The precision of a modern method for body compartment measurements using multiple isotopes

Using readily available beta and gamma detectors, combined measurements of exchangeable sodium, exchangeable potassium, total body water and extracellular fluid volume using the isotopes 24Na, 43K, 3H and 35S were made in ten normal subjects. These measurements were repeated 1-6 weeks later so that an index of precision for each isotope study could be calculated. For such measurements the precision was 55 mmol for exchangeable sodium, 149 mmol for exchangeable potassium, 1.26 litres for total body water and 1.11 litres for extracellular fluid volume. The precision of our method is the best so far reported using readily available apparatus. These results may encourage further studies on different pathological conditions in man to be undertaken in peripheral laboratories.

Hyperlipidaemia diagnosed at lumbar puncture

A patient presenting with subarachnoid haemorrhage and high lipid concentrations in the cerebrospinal fluid (taken at lumbar puncture), who has later shown to have type V hyperlipidaemia is described. This case, so far as can be ascertained by the authors, is the first report of hyperlipidaemia being diagnosed from CSF examination.

Stimulation of residual insulin secretion by glibenclamide in insulin dependent diabetics

Residual insulin secretion, reflected by the presence of C-peptide in serum and urine, has been demonstrated in 5 of 10 insulin-requiring diabetics of less than 10 years' duration tested. The C-peptide response, in the C-peptide secretors, showed a significant increase in both serum and urine after 4 weeks' treatment with 15 mg glibenclamide daily in addition to their usual insulin regime although no beneficial effects in metabolic control were detected. It is suggested that glibenclamide might be a useful adjunct to insulin therapy in insulin-requiring diabetics who still secrete C-peptide.

Hyperglycaemic hyperosmolar non-ketotic diabetic coma presenting as severe dysphagia

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Diabetic twin pregnancy: an unequal result

A diabetic mother produced twins dissimilar in both appearance and blood biochemistry--one being clearly macrosomic and "hyperinsulinised" at delivery, the other apparently normal. It is suggested that the development of fetal hyperinsulinism may depend not only on maternal blood-glucose control but also on fetal blood-supply or genetic factors.

Leptospirosis presenting with profuse haemoptysis

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Disseminated aspergillosis

The history and the clinical and necropsy findings are presented of a patient who died from Aspergillus fumigatus pyaemia occurring as an opportunistic infection complicating a dissecting aortic aneurysm. The diagnosis was made (and treatment instituted) during life: it rested upon repeated isolation of the organism from tracheal aspirations, a positive blood culture and positive serum precipitin reactions to A. fumigatus. Debilitating disease along with large doses of antibiotics and corticosteroids provided the conditions necessary for the normally saphrophytic fungi to become pathogenic. As the therapy for aspergillosis is still ineffective, the danger of prescribing large doses of antibiotics together with corticosteroids is stressed.