Leveraging Chemotype-Specific Resistance for Drug Target Identification and Chemical Biology

Identifying the direct physiological targets of drugs and chemical probes remains challenging. Here we describe how resistance can be used to achieve 'gold-standard' validation of a chemical inhibitor's direct target in human cells. This involves demonstrating that a silent mutation in the target that suppresses inhibitor activity in cell-based assays can also reduce inhibitor potency in biochemical assays. Further, phenotypes due to target inhibition can be identified as those observed in the inhibitor-sensitive cells, across a range of inhibitor concentrations, but not in genetically matched cells with a silent resistance-conferring mutation in the target. We propose that chemotype-specific resistance, which is generally considered to be a limitation of molecularly targeted agents, can be leveraged to deconvolve the mechanism of action of drugs and to properly use chemical probes.

Chemical structure-guided design of dynapyrazoles, cell-permeable dynein inhibitors with a unique mode of action

Cytoplasmic dyneins are motor proteins in the AAA+ superfamily that transport cellular cargos toward microtubule minus-ends. Recently, ciliobrevins were reported as selective cell-permeable inhibitors of cytoplasmic dyneins. As is often true for first-in-class inhibitors, the use of ciliobrevins has in part been limited by low potency. Moreover, suboptimal chemical properties, such as the potential to isomerize, have hindered efforts to improve ciliobrevins. Here, we characterized the structure of ciliobrevins and designed conformationally constrained isosteres. These studies identified dynapyrazoles, inhibitors more potent than ciliobrevins. At single-digit micromolar concentrations dynapyrazoles block intraflagellar transport in the cilium and lysosome motility in the cytoplasm, processes that depend on cytoplasmic dyneins. Further, we find that while ciliobrevins inhibit both dynein's microtubule-stimulated and basal ATPase activity, dynapyrazoles strongly block only microtubule-stimulated activity. Together, our studies suggest that chemical-structure-based analyses can lead to inhibitors with improved properties and distinct modes of inhibition.

DOI:http://dx.doi.org/10.7554/eLife.25174.001

Chromatin Kinases Act on Transcription Factors and Histone Tails in Regulation of Inducible Transcription

The inflammatory response requires coordinated activation of both transcription factors and chromatin to induce transcription for defense against pathogens and environmental insults. We sought to elucidate the connections between inflammatory signaling pathways and chromatin through genomic footprinting of kinase activity and unbiased identification of prominent histone phosphorylation events. We identified H3 serine 28 phosphorylation (H3S28ph) as the principal stimulation-dependent histone modification and observed its enrichment at induced genes in mouse macrophages stimulated with bacterial lipopolysaccharide. Using pharmacological and genetic approaches, we identified mitogen- and stress-activated protein kinases (MSKs) as primary mediators of H3S28ph in macrophages. Cell-free transcription assays demonstrated that H3S28ph directly promotes p300/CBP-dependent transcription. Further, MSKs can activate both signal-responsive transcription factors and the chromatin template with additive effects on transcription. Specific inhibition of MSKs in macrophages selectively reduced transcription of stimulation-induced genes. Our results suggest that MSKs incorporate upstream signaling inputs and control multiple downstream regulators of inducible transcription.

Cytoplasmic Dynein Antagonists with Improved Potency and Isoform Selectivity

Cytoplasmic dyneins 1 and 2 are related members of the AAA+ superfamily (ATPases associated with diverse cellular activities) that function as the predominant minus-end-directed microtubule motors in eukaryotic cells. Dynein 1 controls mitotic spindle assembly, organelle movement, axonal transport, and other cytosolic, microtubule-guided processes, whereas dynein 2 mediates retrograde trafficking within motile and primary cilia. Small-molecule inhibitors are important tools for investigating motor protein-dependent mechanisms, and ciliobrevins were recently discovered as the first dynein-specific chemical antagonists. Here, we demonstrate that ciliobrevins directly target the heavy chains of both dynein isoforms and explore the structure–activity landscape of these inhibitors in vitro and in cells. In addition to identifying chemical motifs that are essential for dynein blockade, we have discovered analogs with increased potency and dynein 2 selectivity. These antagonists effectively disrupt Hedgehog signaling, intraflagellar transport, and ciliogenesis, making them useful probes of these and other cytoplasmic dynein 2-dependent cellular processes.

Design of reversible, cysteine-targeted Michael acceptors guided by kinetic and computational analysis

Electrophilic probes that covalently modify a cysteine thiol often show enhanced pharmacological potency and selectivity. Although reversible Michael acceptors have been reported, the structural requirements for reversibility are poorly understood. Here, we report a novel class of acrylonitrile-based Michael acceptors, activated by aryl or heteroaryl electron-withdrawing groups. We demonstrate that thiol adducts of these acrylonitriles undergo β-elimination at rates that span more than 3 orders of magnitude. These rates correlate inversely with the computed proton affinity of the corresponding carbanions, enabling the intrinsic reversibility of the thiol-Michael reaction to be tuned in a predictable manner. We apply these principles to the design of new reversible covalent kinase inhibitors with improved properties. A cocrystal structure of one such inhibitor reveals specific noncovalent interactions between the 1,2,4-triazole activating group and the kinase. Our experimental and computational study enables the design of new Michael acceptors, expanding the palette of reversible, cysteine-targeted electrophiles.

Targeting protein kinases with selective and semipromiscuous covalent inhibitors

Protein kinase inhibitors are an important class of therapeutics. In addition, selective kinase inhibitors can often reveal unexpected biological insights, augmenting genetic approaches and playing a decisive role in preclinical target validation studies. Nevertheless, developing protein kinase inhibitors with sufficient selectivity and pharmacodynamic potency presents significant challenges. Targeting noncatalytic cysteines with covalent inhibitors is a powerful approach to address both challenges simultaneously. Here, we describe our efforts to design irreversible and reversible electrophilic inhibitors with varying degrees of kinase selectivity. Highly selective covalent inhibitors have been used to elucidate the roles of p90 ribosomal protein S6 kinases in animal models of atherosclerosis and diabetes. By contrast, semipromiscuous covalent inhibitors have revealed new therapeutic targets in disease-causing parasites and have shown utility as chemoproteomic probes for interrogating kinase occupancy in living cells.

Healthcare-associated outbreak of meticillin-resistant Staphylococcus aureus bacteraemia: role of a cryptic variant of an epidemic clone

Background

New strains of meticillin-resistant Staphylococcus aureus (MRSA) may be associated with changes in rates of disease or clinical presentation. Conventional typing techniques may not detect new clonal variants that underlie changes in epidemiology or clinical phenotype.

Aim

To investigate the role of clonal variants of MRSA in an outbreak of MRSA bacteraemia at a hospital in England.

Methods

Bacteraemia isolates of the major UK lineages (EMRSA-15 and -16) from before and after the outbreak were analysed by whole-genome sequencing in the context of epidemiological and clinical data. For comparison, EMRSA-15 and -16 isolates from another hospital in England were sequenced. A clonal variant of EMRSA-16 was identified at the outbreak hospital and a molecular signature test designed to distinguish variant isolates among further EMRSA-16 strains.

Findings

By whole-genome sequencing, EMRSA-16 isolates during the outbreak showed strikingly low genetic diversity (P < 1 × 10⁻⁶, Monte Carlo test), compared with EMRSA-15 and EMRSA-16 isolates from before the outbreak or the comparator hospital, demonstrating the emergence of a clonal variant. The variant was indistinguishable from the ancestral strain by conventional typing. This clonal variant accounted for 64/72 (89%) of EMRSA-16 bacteraemia isolates at the outbreak hospital from 2006.

Conclusions

Evolutionary changes in epidemic MRSA strains not detected by conventional typing may be associated with changes in disease epidemiology. Rapid and affordable technologies for whole-genome sequencing are becoming available with the potential to identify and track the emergence of variants of highly clonal organisms.

Electrophilic fragment-based design of reversible covalent kinase inhibitors

Fragment-based ligand design and covalent targeting of noncatalytic cysteines have been employed to develop potent and selective kinase inhibitors. Here, we combine these approaches, starting with a panel of low-molecular-weight, heteroaryl-susbstituted cyanoacrylamides, which we have previously shown to form reversible covalent bonds with cysteine thiols. Using this strategy, we identify electrophilic fragments with sufficient ligand efficiency and selectivity to serve as starting points for the first reported inhibitors of the MSK1 C-terminal kinase domain. Guided by X-ray co-crystal structures, indazole fragment 1 was elaborated to afford 12 (RMM-46), a reversible covalent inhibitor that exhibits high ligand efficiency and selectivity for MSK/RSK-family kinases. At nanomolar concentrations, 12 blocked activation of cellular MSK and RSK, as well as downstream phosphorylation of the critical transcription factor, CREB.

Qualitative effects of fresh and dried plum ingredients on vacuum-packaged, sliced hams

Boneless ham muscles (Semimembranosus+Adductor) were injected (20% w/w) with a curing brine containing no plum ingredient (control), fresh plum juice concentrate (FP), dried plum juice concentrate (DP), or spray dried plum powder (PP) at 2.5% or 5%. Hams were cooked, vacuum-packaged, stored at<4°C and evaluated at 2-week intervals over 10 week. Evaluations were performed on sliced product to determine cook loss, vacuum-package purge, Allo-Kramer shear force, 2-thiobarbituric acid-reactive substances (TBARS), proximate analysis, objective color, sensory panel color and sensory attributes. FP, DP and 2.5% PP increased (P<0.05) cook loss by 2% to 7% depending on treatment and level, but the highest cook loss (17.7%) was observed in hams with 5% PP. Shear force values increased as the level of plum ingredient increased (P<0.05) from 2.5% to 5%, and the highest shear values were observed in hams containing 5% FP. There were no differences (P>0.05) in lipid oxidation among treatments as determined by TBARS and sensory evaluation. FP and PP ham color was similar to the control, but DP had a more intense atypical color of cured ham. Minimal changes in physical, chemical and sensory properties were observed during storage of all treatments.

Temporal changes in C and N stocks of restored prairie: implications for C sequestration strategies

The recovery of ecosystem C and N dynamics after disturbance can be a slow process. Chronosequence approaches offer unique opportunities to use space-for-time substitution to quantify the recovery of ecosystem C and N stocks and estimate the potential of restoration practices for C sequestration. We studied the distribution of C and N stocks in two chronosequences that included long-term cultivated lands, 3- to 26-year-old prairie restorations, and remnant prairie on two related soil series. Results from the two chronosequences did not vary significantly and were combined. Based on modeling predictions, the recovery rates of different ecosystem components varied greatly. Overall, C stocks recovered faster than N stocks, but both C and N stocks recovered more rapidly for aboveground vegetation than for any other ecosystem component. Aboveground C and N reached 95% of remnant levels in only 13 years and 21 years, respectively, after planting to native vegetation. Belowground plant C and N recovered several decades later, while microbial biomass C, soil organic C (SOC), and total soil N recovered on a century timescale. In the cultivated fields, SOC concentrations were depleted within the surface 25 cm, coinciding with the depth of plowing, but cultivation apparently led to redistribution of soil C, increasing SOC stocks deeper in the soil profile. The restoration of prairie vegetation was effective at rebuilding soil organic matter (SOM) in the surface soil. Accrual rates were maintained at 43 g C x m(-2) x yr(-1) and 3 g N x m(-2) x yr(-1) in the surface 0.16 Mg/m2 soil mass during the first 26 years of restoration and were predicted to reach 50% of their storage potential (3500 g C/m2) in the first 100 years. We conclude that restoration of tallgrass prairie vegetation can restore SOM lost through cultivation and has the potential to sequester relatively large amounts of SOC over a sustained period of time. Whether restored prairies can retain the C apparently transferred to the subsoil by cultivation practices remains to be seen.

Isoform-specific effects of ApoE on HSV immediate early gene expression and establishment of latency

Alzheimer's disease (AD) is a common and devastating neurodegenerative disease in which most cases are of unknown, sporadic origin. In addition to age, the most prevalent known risk factor for developing AD is carriage of the epsilon4 allele of Apolipoprotein E (ApoE). Carriage of the epsilon2 or epsilon3 allele of ApoE confers protection or no change in risk for AD, respectively. Latent herpes simplex virus type 1 (HSV-1) infection in the brain concurrent with ApoE4 carriage exacerbates risk for AD, suggesting that these two factors interact to promote neuronal dysfunction and degeneration in selective brain areas. Indeed, HSV-1 DNA has been found in regions primarily affected by AD, such as the temporal lobes, hippocampus, and neocortex. We hypothesize that HSV-1 infection in the background of ApoE4, but not ApoE2 or ApoE3, promotes an environment more conducive to neuronal degeneration. To investigate this idea, we have utilized transgenic mice that express human ApoE2, 3, or 4 alleles from astrocytes in a murine ApoE -/- background. We find that carriage of the different ApoE alleles dramatically affects HSV-1 immediate early gene expression as well as the establishment of latency. Both of these factors are poised to impact neuronal viability, inflammation, and viral spread. Our data support the concept that HSV-1 and ApoE4 interact to provide an environment conducive to the development and/or spread of AD.

Memories and anticipations control responding by rats (Rattus norvegicus) in a Pavlovian procedure

In Experiment 1 each rat received two different fixed series of three trials each. The unconditioned stimulus occurred on Trial 1 of one series and on Trial 3 of the other series, all other trials being nonreinforced. Previous Pavlovian investigations have shown that rats can remember the immediately prior reward outcome and anticipate the immediately subsequent reward outcome. Experiment 1 demonstrated that rats could remember and anticipate even more remote reward outcomes. In Experiment 2 two groups received a series of two nonrewarded trials followed by a rewarded trial. It was demonstrated that a change in the conditioned stimulus (CS) from Trial 2 to Trial 3, which occurred in one group, produced weaker responding than in the other group that did not experience such CS change. On the basis of these findings it was suggested that the rats organized the trials of a series into a unit or chunk. This was concluded for two reasons. First, remembering and anticipating remote reward outcomes strongly suggests that responding is being controlled by events extending beyond the current trial. Secondly, the experimental manipulations employed in the Pavlovian situation here are similar to those used in prior human learning and animal instrumental learning investigations concerned with chunking. Thus, it would appear that chunking is a ubiquitous phenomenon appearing in human serial learning (e.g., Bower and Winzenz 1969; Crowder 1976), in animal instrumental learning (e.g., Capaldi 1992; Hulse and Dorsky 1977; Terrace 1987), and now in Pavlovian learning.

CCS/CAR/CANM/CNCS/CanSCMR joint position statement on advanced noninvasive cardiac imaging using positron emission tomography, magnetic resonance imaging and multidetector computed tomographic angiography in the diagnosis and evaluation of ischemic heart disease--executive summary

BACKGROUND

Over the past few decades, advanced imaging modalities with excellent diagnostic capabilities have emerged. The aim of the present position statement was to systematically review existing literature to define Canadian recommendations for their clinical use.

METHODS

A systematic literature review to 2005 was conducted for positron emission tomography (PET), multidetector computed tomographic angiography and magnetic resonance imaging (MRI) in ischemic heart disease. Papers that met the criteria were reviewed for accuracy, prognosis data and study quality. Recommendations were presented to primary and secondary panels of experts, and consensus was achieved.

RESULTS

Indications for PET include detection of coronary artery disease (CAD) with perfusion imaging, and defining viability using fluorodeoxyglucose to determine left ventricular function recovery and/or prognosis after revascularization (class I). Detection of CAD in patients, vessel segments and grafts using computed tomographic angiography was considered class IIa at the time of the literature review. Dobutamine MRI is class I for CAD detection and, along with late gadolinium enhancement MRI, class I for viability detection to predict left ventricular function recovery. Imaging must be performed at institutions and interpreted by physicians with adequate experience and training.

CONCLUSIONS

Cardiac imaging using advanced modalities (PET, multidetector computed tomographic angiography and MRI) is useful for CAD detection, viability definition and, in some cases, prognosis. These modalities complement the more widespread single photon emission computed tomography and echocardiography. Given the rapid evolution of technology, initial guidelines for clinical use will require regular updates. Evaluation of their integration in clinical practice should be ongoing; optimal use will require proper training. A joint effort among specialties is recommended to achieve these goals.

Temporal evolution of mouse striatal gene expression following MPTP injury

The gradual loss of striatal dopamine and dopaminergic neurons residing in the substantia nigra (SN) causes parkinsonism characterized by slow, halting movements, rigidity, and resting tremor when neuronal loss exceeds a threshold of approximately 80%. It is estimated that there is extensive compensation for several years prior to symptom onset, during which vulnerable neurons asynchronously die. Recent evidence would argue that much of the compensatory response of the nigrostriatal system is multimodal including both pre-synaptic and striatal mechanisms. Although parkinsonism may have multiple causes, the classic syndrome, Parkinson's disease (PD), is frequently modeled in small animals by repeated administration of the selective neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Because the MPTP model of PD recapitulates many of the known behavioral and pathological features of human PD, we asked whether the striatal cells of mice treated with MPTP in a semi-chronic paradigm enact a transcriptional program that would help elucidate the response to dopamine denervation. Our findings reveal a time-dependent dysregulation in the striatum of a set of genes whose products may impact both the viability and ability to communicate of dopamine neurons in the SN.

Mycorrhizal mediated feedbacks influence net carbon gain and nutrient uptake in Andropogon gerardii

•  The carbon sink strength of arbuscular mycorrhizal fungi (AMF) was investigated by comparing the growth dynamics of mycorrhizal and nonmycorrhizal Andropogon gerardii plants over a wide range of equivalent tissue phosphorus : nitrogen (P : N) ratios. •  Host growth, apparent photosynthesis (A_net ), net C gain (C_n ) and P and N uptake were evaluated in sequential harvests of mycorrhizal and nonmycorrhizal A. gerardii plants. Response curves were used to assess the effect of assimilate supply on the mycorrhizal symbiosis in relation to the association of C with N and P. •  Mycorrhizal plants had higher C_n than nonmycorrhizal plants at equivalent shoot P : N ratios even though colonization did not affect plant dry mass. The higher C_n in mycorrhizal plants was related to both an increase in specific leaf area and enhanced photosynthesis. The additional carbon gain associated with the mycorrhizal condition was not allocated to root biomass. The C_n in the mycorrhizal plants was positively related to the proportion of active colonization in the roots. •  The calculated difference between C_n values in mycorrhizal and nonmycorrhizal plants, C_diff , appeared to correspond to the sink strength of the AMF and was not an indirect result of enhanced nutrition in mycorrhizal plants.

Behavior and Misbehavior of the Horse

For decades after the discipline of psychiatry had been established as an accepted specialty, many medical schools continued to fail to train their students in the fundamentals of this discipline. Medical students all have at least cursory exposure to psychiatric principles and basic psychology. Unfortunately, the veterinary profession has lagged behind human medicine in this regard. Until recently, veterinary students received no training in animal behavior, and there were no available residencies within our schools for developing board-certified behavioral specialists.

Coping with metastatic melanoma: the last year of life

BACKGROUND

Few longitudinal studies have concurrently investigated cognitive appraisal, coping and psychological adjustment in patients with terminal cancer. This study aimed to (i) consider patterns of change in these variables during the last year of life and (ii) consider covariates associated with patients' psychological adjustment.

METHODS AND PATIENTS

Questionnaires were sent to a cohort of stage IV melanoma patients seen at the Sydney Melanoma Unit between 1991 and 1996, approximately every 3 months, for up to 2 years. A sub-sample of 110 patients completed at least one questionnaire in the last year of life. Repeated measures linear regression was used to model cognitive appraisal, coping and psychological adjustment.

RESULTS

In the last year of life, patients' cognitive appraisal of their disease remained relatively stable, whereas their use of active coping strategies increased (p=0. 04). There was some deterioration in psychological adjustment, particularly in patients' ability to minimize the impact of cancer on daily life (p=0.03), but this effect did not remain significant when patients' level of tiredness was included in the model. Cognitive appraisal, coping style and quality of life indicators were all associated with psychological adjustment.

CONCLUSION

These findings suggest that while patients work hard to actively cope with their disease, they experience increasing levels of tiredness, and deterioration in their mood and ability to function in their daily lives.

Thrombosed giant coronary artery aneurysm presenting as an intracardiac mass

Giant coronary artery aneurysms are rare in adults and are usually found in association with Kawasaki's disease arising in childhood. We report a case of a thrombosed giant right coronary artery aneurysm presenting as an intracardiac mass detected after inferior wall myocardial infarction. Histologic analysis indicated that fibromuscular dysplasia was the underlying cause of the aneurysm.

Advances in the management of dysphagia caused by stroke

This article reviews the advancements that have occurred, primarily in the last decade, in the management and treatment of swallowing disorders related to stroke. An overview of swallowing physiology is given, and interventions, both indirect and direct, are explored. Expanding knowledge, applying techniques from other scientific disciplines, and developing new technologies provide hope for stroke patients who experience dysphagia.

Mycorrhizal status of the genus Carex (Cyperaceae)

The Cyperaceae have generally been considered nonmycorrhizal, although recent evidence suggests that mycotrophy may be considerably more widespread among sedges than was previously realized. This study surveyed 23 species of Carex occurring in upland and wetland habitats in northeastern Illinois. Mycorrhizal infection by arbuscular fungi was found in the roots of 16 species of Carex and appears to occur in response to many factors, both environmental and phylogenetic. While some species appear to be obligately nonmycorrhizal, edaphic influences may be responsible for infection in others. In five of the seven Carex species that were nonmycorrhizal, a novel root character, the presence of bulbous-based root hairs, was identified. The taxonomically patchy distribution of the distinctive root hair trait suggests that these structures may have evolved several times within the genus. Evidence of multiple independent origins of the root hair trait lends support to the hypothesis that root hairs represent an adaptation to nonmycotrophy. Although taxonomic position does seem to be of importance in determining the mycorrhizal dependence of sedges, the pattern may be a patchwork of both mycorrhizal clades and clades that have adapted to the nonmycorrhizal state.

Stroke: current concepts of care

Despite the approval of the use of tissue plasminogen activator for the treatment of acute stroke, less than 10% of all patients with stroke are able to reach a medical facility in time to receive the treatment. This article reviews the current concepts of stroke management and emphasizes the importance of public awareness for the signs and symptoms of stroke and the need for immediate attention when a stroke is suspected.

Benign hypergammaglobulinaemic purpura of Waldenström associated with lymphoid interstitial pneumonitis

A 31-year-old female is described who developed benign hypergammaglobulinaemic purpura and lymphoid interstitial pneumonitis concomitantly. High titre anti-nuclear antibodies were also noted. Several years previously, the patient had developed myasthenia gravis and multiple sclerosis. The present case is an example of multiple medical disorders characterized by immune dysregulation and represents the first reported associated of hypergammaglobulinaemic purpura with lymphoid interstitial pneumonitis.

X-ray imaging and microspectroscopy of plants and fungi

X-ray fluorescence microscopy and microspectroscopy with micrometre spatial resolution and unprecedented capabilities for the study of biological and environmental samples are reported. These new capabilities are a result of both the combination of high-brilliance synchrotron radiation and high-performance X-ray microfocusing optics and the intrinsic advantages of X-rays for elemental mapping and chemical-state imaging. In this paper, these capabilities are illustrated by experimental results on hard X-ray phase-contrast imaging, X-ray fluorescence (XRF) imaging and microspectroscopy of mycorrhizal plant roots and fungi in their natural hydrated state. The XRF microprobe is demonstrated by the simultaneous mapping of the elemental distributions of P, S, K, Ca, Mn, Fe, Ni, Cu and Zn with a spatial resolution of approximately 1 x 3 micron and with an elemental sensitivity of approximately 500 p.p.b. Microspectroscopy with the same spatial resolution is demonstrated by recording near-edge X-ray absorption (XANES) spectra of Mn at a concentration of approximately 3 p.p.m.

Dysphagia caused by neurologic deficits

This article provides a brief review of the neurophysiology behind the normal swallow. The examination and work-up of a patient with dysphagia is then detailed. Finally, the major neurologic conditions associated with dysphagia are considered.

Antineutrophil cytoplasmic antibody (ANCA)-positive cutaneous leucocytoclastic vasculitis associated with antithyroid therapy in Graves' disease

Presented is a case of a 27-year-old male with Graves' disease on long-term propylthiouracil treatment who, when changed to carbimazole, rapidly developed a petechial and purpuric eruption on the legs, which subsequently flared on treatment with radioiodine. The clinical diagnosis of leucocytoclastic vasculitis was confirmed on skin biopsy. High-titre antineutrophil cytoplasmic antibodies in a perinuclear pattern (P-ANCA) were identified. No anti-myeloperoxidase activity was noted; therefore, the P-ANCA were classified in the atypical group. The target antigens, as determined by enzyme-linked immunosorbent assay, were lysozyme, lactoferrin and bactericidal/permeability increasing protein. Propylthiouracil and carbimazole are chemically related antithyroid drugs. There are reports of typical and atypical P-ANCA-positive cutaneous vasculitis due to propylthiouracil. Cutaneous vasculitis associated with atypical P-ANCA has not been noted previously to be temporally related to carbimazole use. The consideration of thionamides as possible aetiological agents in cases of P-ANCA-positive drug-induced vasculitis is suggested.

The location of the intervertebral lumbar disc on the posterior aspect of the spine

BACKGROUND

Epidural fibrosis or scar formation is considered one cause of failed lumbar discectomy. Avoidance of unnecessary bony resection of the lamina may prevent or decrease postoperative scar formation. The knowledge of the precise location of the projection of the lumbar disc may also facilitate surgery and decrease patient morbidity. No studies exist regarding the projection of the lumbar disc on the posterior aspect of the lumbar spine.

METHODS

Thirty-six whole lumbar spine specimens from L1 to L5 (180 lumbar vertebrae) and sacra were used for this study. Anatomic evaluation included the distance between the superior border of the vertebral body (inferior border of the intervertebral disc) and the superiormost margin of the lumbar lamina, and the distance between the inferior border of the vertebral body (superior border of the intervertebral disc) and the inferiormost margin of the lumbar lamina. The width of the interlaminar space was also measured.

RESULTS

The data showed that the level of the superior margin of the lamina was consistently inferior to the superior border of the corresponding vertebral body from L1 to S1. This distance for both sexes ranged from 10 to 11 mm for L1-L5 and 14 mm for S1. The level of the inferior margin of the lamina varied from 3 mm inferior to 9 mm superior to the inferior border of the corresponding vertebral body for L1-L5. The width of the interlaminar space averaged from 16.8 mm for L1 to 31.0 mm for L5.

CONCLUSIONS

This study suggests that the superior margin of the lamina represents a consistent, useful landmark in determining the location of the lumbar disc on the posterior aspect of the spine. The relationship between the inferior margins of the lamina and the vertebral body is not consistent.

Rhamnolipid (biosurfactant) effects on cell aggregation and biodegradation of residual hexadecane under saturated flow conditions

The objective of this research was to evaluate the effect of low concentrations of a rhamnolipid biosurfactant on the in situ biodegradation of hydrocarbon entrapped in a porous matrix. Experiments were performed with sand-packed columns under saturated flow conditions with hexadecane as a model hydrocarbon. Application of biosurfactant concentrations greater than the CMC (the concentration at which the surfactant molecules spontaneously form micelles or vesicles [0.03 mM]) resulted primarily in the mobilization of hexadecane entrapped within the sand matrix. In contrast, application of biosurfactant concentrations less than the CMC enhanced the in situ mineralization of entrapped hexadecane; however, this effect was dependent on the choice of bacterial isolate. The two Pseudomonas isolates tested, R4 and ATCC 15524, were used because they exhibit different patterns of biodegradation of hexadecane, and they also differed in their physical response to rhamnolipid addition. ATCC 15524 cells formed extensive multicell aggregates in the presence of rhamnolipid while R4 cells were unaffected. This behavior did not affect the ability of the biosurfactant to enhance the biodegradation of hexadecane in well-mixed soil slurry systems but had a large affect on the extent of entrapped hexadecane biodegradation in the sand-packed-column system that was used in this study.

Selection and partial characterization of a Pseudomonas aeruginosa mono-rhamnolipid deficient mutant

Pseudomonas aeruginosa produces rhamnolipids which are tenso-active compounds with potential industrial and environmental applications. There are two main types of rhamnolipids produced in liquid cultures, rhamnosyl-beta-hydroxydecanoyl-beta-hydroxydecanoate (mono-rhamnolipid) and rhamnosyl-rhamnosyl-beta-hydroxydecanoyl-beta-hydroxyd ecanoate (di-rhamnolipid). In this work we report the selective isolation of a rhamnolipid deficient mutant (IBT8), which does not accumulate mono-rhamnolipid while still producing di-rhamnolipid. IBT8 was selected after random mutagenesis with Tn501; yet, its mono-rhamnolipid deficiency was found associated neither with its Tn501 insertion nor with a possible alteration in the rhlABRI genes for rhamnosyl-transferase 1 synthesis. Different possibilities to explain IBT8 phenotype are discussed.

Goserelin acetate (Zoladex) plus endometrial ablation for dysfunctional uterine bleeding: a large randomized, double-blind study

OBJECTIVE

To confirm the advantages of goserelin prior to endometrial ablation for the treatment of dysfunctional uterine bleeding.

DESIGN

Multicenter, prospective, randomized, double-blind study.

PATIENT(S)

Cycling premenopausal women with dysfunctional uterine bleeding.

TREATMENT

Patients were randomized to goserelin or placebo (sham depot) once monthly for 2 months prior to endometrial ablation. Treatment was timed to allow surgery 6 weeks later on day 7 of the menstrual cycle.

MAIN OUTCOME MEASURE(S)

Amenorrhea rates, endometrial histology and thickness, pain and blood loss scores, and surgical parameters.

RESULT(S)

At 24 weeks after surgery, significantly more goserelin than placebo patients experienced amenorrhea (40% versus 26%). Blood loss was reduced from baseline, but not different between the groups. At surgery, mean endometrial thickness was 1.6 mm and 3.4 mm for the goserelin and placebo groups, respectively, with significantly more atrophic glands and stroma in the goserelin group. Surgery was significantly shorter (by 22%) and easier in the goserelin than in the placebo group, with a significantly lower median fluid absorption in the goserelin groups. In both groups, pain scores were reduced patient satisfaction was high (> 92%), and re-intervention rate was low (2.8%).

CONCLUSION(S)

Goserelin in combination with endometrial ablation was superior to endometrial ablation alone for the treatment of dysfunctional uterine bleeding.

Influence of a Rhamnolipid Biosurfactant on the Transport of Bacteria through a Sandy Soil

The objective of this study was to investigate the influence of an anionic rhamnolipid biosurfactant on the transport of bacterial cells through soil under saturated conditions. Three cell types with various hydrophobicities, i.e., Pseudomonas aeruginosa ATCC 9027, ATCC 27853, and ATCC 15442, were used in this study. In a series of experiments, columns packed with sterile sand were saturated with sterile artificial groundwater for 15 h, and then 3 pore volumes of (sup3)H-labeled bacterial suspensions with various rhamnolipid concentrations was pumped through the column. This was followed by 4 pore volumes of the rhamnolipid solution alone. The measured bacterial cell breakthrough curves were optimized by using an advection-dispersion transport model incorporating two-domain reversible sorption (instantaneous and rate limited) and with two first-order sink terms for irreversible adsorption. The influence of the rhamnolipid on the surface charge densities of the bacteria and the porous medium was also investigated. The results show that the rhamnolipid enhanced the transport of all cell types tested. For example, the rhamnolipid increased the recovery of the most hydrophilic strain, ATCC 9027, from 22.5 to 56.3%. Similarly, the recovery of ATCC 27853 increased from 36.8 to 49.4%, and the recovery of ATCC 15442, the most hydrophobic strain, increased from 17.7 to 40.5% in the presence of the rhamnolipid. The negative surface charge density of the porous medium was increased, while the surface charge density of the bacteria was not changed in the presence of the rhamnolipid. The model results suggest that the rhamnolipid predominantly affected irreversible adsorption of cells.

Transfection with aFGF cDNA improves wound healing

Somatic gene therapy is a potentially useful strategy for the delivery of growth factors or cytokines to enhance wound healing. Experimental excisional and incisional wounds in impaired-healing diabetic mice (db/db) were treated with aFGF and with a plasmid coding for aFGF. A eukaryotic expression plasmid composed of the Hst signal peptide sequence in-frame with the human aFGF sequence was used. Transfection of tissues was accomplished either by direct plasmid uptake or by uptake facilitated with cationic liposomes. The results show that the closure of excisional wounds was significantly accelerated (p < 0.05) by topical application of human recombinant aFGF or by transfection with the aFGF plasmid but not by vehicle or control plasmid not containing the aFGF sequence. In incisional wounds, aFGF or transfection with the plasmid significantly increased the wound-breaking strength compared to their corresponding controls (p < 0.05). Quantitative histology of the plasmid-treated incisional wound sections revealed improved wound quality. The transcription of mRNA from human aFGF cDNA in the incisional wound tissue extracts was confirmed by RT-PCR, and the expressed aFGF was detected by immune dot blot and immunohistochemistry assays. The transfection was a transient process with a peak at 9 d in db/+ (littermates of the diabetic mice) incisional wounds, at 36 d in db/db incisional wounds, and at 27 d in db/db excisional wounds. Cells transfected with human aFGF occupied up to 6.4% of the transectional area in the wound sites. Thus, aFGF gene delivery resulted in both gene expression and a functional improvement in healing.

Anatomic consideration of transpedicular screw placement in the cervical spine. An analysis of two approaches

STUDY DESIGN

This study compared the effectiveness of two transpedicular screw placement techniques: blind screw placement versus screw placement after direct determination of the superior, medial, and inferior borders of the pedicle through the opening of a "window" by the partial laminectomy and tapping technique.

OBJECTIVES

To determine if the incidence and severity of pedicle violations resulting from transpedicular screw placement could be reduced by direct determination of the superior, medial, and inferior borders of the pedicle through the opening of a "window" by partial laminectomy.

SUMMARY OF BACKGROUND DATA

Several studies regarding transpedicular screw fixation for unstable cervical spine injuries have been reported, but none has addressed the effectiveness in lowering the incidence of pedicle violation by opening a "window" by partial laminectomy for direct determination of the superior, medial, and inferior borders of the pedicle and using the tapping technique before and in planning for screw placement.

METHODS

Eight adult cadaveric cervical spines (40 vertebrae from C3 to C7) were used for this study. Two groups were formed according to screw placement techniques. The first group was composed of 38 blinded transpedicular screw placements. The second group was composed of 40 screw placements using the partial laminectomy and tapping technique. After transpedicular screw placement, all specimens were evaluated radiographically and visually for violation of the pedicle.

RESULTS

A decrease in the incidence and severity of pedicle violation was seen in the second group with opening of the lamina and tapping technique compared with the blind screw placement group. However, the percentage of screws found to violate the pedicle with the opening of the lamina and tapping technique still was relatively high.

CONCLUSIONS

Transpedicular screw placement in the cervical spine is difficult, and a high percentage of violations of the pedicle wall occur. This technique should not be used routinely.

Management of oral-pharyngeal dysphagia symptoms in amyotrophic lateral sclerosis

Oral and pharyngeal dysphagia is a common symptom in patients with amyotrophic lateral sclerosis (ALS) and is the result of a progressive loss of function in bulbar and respiratory muscles. Clinicians involved in the management of ALS patients should be familiar with the common clinical findings and the usual patterns of temporal progression. The prevention of secondary complications, such as nutritional deficiency and dehydration that compound the deteriorating effects of the disease, requires careful monitoring of each patient's functional status and timely intervention with appropriate management techniques.

Effect of Rhamnolipid (Biosurfactant) Structure on Solubilization and Biodegradation of n-Alkanes

A study to quantify the effect of rhamnolipid biosurfactant structure on the degradation of alkanes by a variety of Pseudomonas isolates was conducted. Two dirhamnolipids were studied, a methyl ester form (dR-Me) and an acid form (dR-A). These rhamnolipids have different properties with respect to interfacial tension, solubility, and charge. For example, the interfacial tension between hexadecane and water was decreased to <0.1 dyne/cm by the dR-Me but was only decreased to 5 dyne/cm by the dR-A. Solubilization and biodegradation of two alkanes in different physical states, liquid and solid, were determined at dirhamnolipid concentrations ranging from 0.01 to 0.1 mM (7 to 70 mg/liter). The dR-Me markedly enhanced hexadecane (liquid) and octadecane (solid) degradation by seven different Pseudomonas strains. For an eighth strain tested, which exhibited extremely high cell surface hydrophobicity, hexadecane degradation was enhanced but octadecane degradation was inhibited. The dR-A also enhanced hexadecane degradation by all degraders but did so more modestly than the dR-Me. For octadecane, the dR-A only enhanced degradation by strains with low cell surface hydrophobicity.

Biosurfactant-facilitated remediation of metal-contaminated soils

Bioremediation of metal-contaminated wastestreams has been successfully demonstrated. Normally, whole cells or microbial exopolymers are used to concentrate and/or precipitate metals in the wastestream to aid in metal removal. Analogous remediation of metal-contaminated soils is more complex because microbial cells or large exopolymers do not move freely through the soil. The use of microbially produced surfactants (biosurfactants) is an alternative with potential for remediation of metal-contaminated soils. The distinct advantage of biosurfactants over whole cells or exopolymers is their small size, generally biosurfactant molecular weights are less than 1500. A second advantage is that biosurfactants have a wide variety of chemical structures that may show different metal selectivities and thus, metal removal efficiencies. A review of the literature shows that complexation capacities of several bacterial exopolymers was similar to the complexation capacity of a rhamnolipid biosurfactant produced by Pseudomonas aeruginosa ATCC 9027.

Application of an electrocardiographic inverse solution to localize ischemia during coronary angioplasty

Localization of Ischemia. This study demonstrates the utility of an electrocardiographic inverse solution, coupled with body surface potential mapping (BSPM), in localizing acute ischemia in patients undergoing percutaneous transluminal coronary angioplasty (PTCA). PTCA balloon inflations produce complete occlusion and acute transient ischemia, which can be detected electrocardiographically with BSPM. Comparisons between maps recorded both during and before the inflation of the PTCA balloon allow patient- and artery-specific characterizations of the resulting ischemia. Knowledge of the patient's coronary anatomy and the location of the occlusion site by coronary angiography permit an estimation based on cardiac hemodynamics of the region of myocardium most likely to suffer from PTCA-induced ischemia. Electrocardiographic inverse solutions provide a means of predicting cardiac potentials from body surface maps. In this study, we describe an inverse solution we have developed to localize the transient ischemia produced by PTCA. To validate the procedure, we compared the locations of predicted ischemia in seven patients with a qualitative estimate of the perfusion region based on fluoroscopic examination of each patient's coronary anatomy and PTCA balloon location. In each case, the region of ischemia predicted by the model included the perfusion zone determined fluoroscopically. These results suggest that electrical changes induced by acute ischemia can be localized with an electrocardiographic inverse solution.