Spectroscopic insights with molecular docking and molecular dynamic simulation studies of anticancer drug 5-Fluorouracil targeting human pyruvate kinase m2

This study was conducted to test the efficacy of 5-fluorouracil (5-FU) as an anticancer drug against the human pyruvate kinase isozyme M2 (PKM2) using spectroscopic, molecular docking and molecular dynamic simulation studies. PKM2 fluorescence quenching studies in the presence of 5-FU performed at three different temperatures indicates dynamic quenching processes with single-set of binding (n ≈ 1) profile. The biomolecular quenching constants (kq) and the effective binding constants (Kb) obtained are shown to increase with temperature. The calculated enthalpy (ΔH) and entropy changes (ΔS) are estimated to be -118.06 kJ/mol and 146.14 kJ/mol/K respectively, which suggest the possible mode of interaction as electrostatic and hydrogen bonding. Further, these values were used to estimate the free energy changes (ΔG) and that increases with temperature. The negative ΔG values clearly indicates spontaneous binding process that stabilizes the complex formed between 5-FU and PKM2. Far-UV CD spectra of PKM2 in the presence of 5-FU shows decrease in α-helix contents which point towards the destabilization of secondary structure that weakens the biological activity of PKM2. The intrinsic fluorescence study and circular dichroism (CD) spectra showed minor conformational changes of PKM2 in the presence of 5-FU. Additionally, the results obtained from molecular docking and all-atom molecular dynamic simulation study supports the insight of the spectroscopic binding studies, and strengthens the dynamic stability of the complex between 5-FU and PKM2 through H-bonding. This study establishes a paradigm of 5-FU-PKM2 complexation and the efficacy of 5-FU that compromises the biological activity of the targeted PKM2.Communicated by Ramaswamy H. Sarma.

Cephem-Pyrazinoic Acid Conjugates: Circumventing Resistance in Mycobacterium tuberculosis

Tuberculosis (TB) is a leading source of infectious disease mortality globally. Antibiotic-resistant strains comprise an estimated 10 % of new TB cases and present an urgent need for novel therapeutics. β-lactam antibiotics have traditionally been ineffective against M. tuberculosis (Mtb), the causative agent of TB, due to the organism's inherent expression of β-lactamases that destroy the electrophilic β-lactam warhead. We have developed novel β-lactam conjugates, which exploit this inherent β-lactamase activity to achieve selective release of pyrazinoic acid (POA), the active form of a first-line TB drug. These conjugates are selectively active against M. tuberculosis and related mycobacteria, and activity is retained or even potentiated in multiple resistant strains and models. Preliminary mechanistic investigations suggest that both the POA "warhead" as well as the β-lactam "promoiety" contribute to the observed activity, demonstrating a codrug strategy with important implications for future TB therapy.

Placental DNA methylation changes in detection of tetralogy of Fallot

OBJECTIVES

To determine whether the methylation level of cytosine nucleotides in placental DNA can be used to predict tetralogy of Fallot (TOF) and provide insights into the developmental mechanism of this condition.

METHODS

Tissue sections were obtained from formalin-fixed paraffin-embedded specimens of placental tissue obtained at birth from eight cases with non-chromosomal, non-syndromic TOF and 10 unaffected newborns. The Illumina Infinium HumanMethylation450 BeadChip assay was used to measure cytosine ('CpG' or 'cg') methylation levels at loci throughout the placental genome. Differential methylation was assessed by comparing the β-values (a measure of the extent of cytosine methylation) for individual CpG loci in fetuses with TOF vs in controls. The most discriminating CpG sites were determined based on a preset cut-off of ≥ 2.0-fold change in the methylation level. The predictive accuracy of CpG loci with significant methylation changes for TOF was determined by the area under the receiver-operating-characteristics curve (AUC). A false-discovery-rate (FDR) P-value < 0.05 was used to define a statistically significant difference in the methylation level. Ingenuity Pathway Analysis (IPA) (Qiagen) was used to identify gene pathways that were significantly overexpressed, and thus altered, in TOF cases compared with controls.

RESULTS

We found a total of 165 significantly differentially methylated CpG loci in TOF cases compared with controls, in 165 separate genes. These biomarkers demonstrated from fair to excellent individual predictive accuracy for TOF detection, with AUCs ≥ 0.75 (FDR P-value < 0.001 for all). The following CpG loci (gene) had the highest predictive accuracy: cg05273049 (ARHGAP22; AUC = 1.00; 95% CI, 1.00-1.00), cg02540011 (CDK5; AUC = 0.96; 95% CI, 0.87-1.00), cg08404201 (TRIM27; AUC = 0.95; 95% CI, 0.84-1.00) and cg00687252 (IER3; AUC = 0.95; 95% CI, 0.84-1.00). IPA revealed over-representation (dysregulation) of 14 gene pathways involved in normal cardiac development, including cardiomyocyte differentiation via bone morphogenetic protein receptors, cardiac hypertrophy signaling and role of nuclear factor of activated T cells in cardiac hypertrophy. Cardiac hypertrophy is an important feature of TOF.

CONCLUSIONS

Analysis of placental DNA cytosine methylation changes yielded accurate markers for TOF detection and provided mechanistic information on TOF development. Our work appears to confirm the central role of epigenetic changes and of the placenta in the development of TOF. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Investigation of ( S)-(-)-Acidomycin: A Selective Antimycobacterial Natural Product That Inhibits Biotin Synthase

The synthesis, absolute stereochemical configuration, complete biological characterization, mechanism of action and resistance, and pharmacokinetic properties of ( S)-(-)-acidomycin are described. Acidomycin possesses promising antitubercular activity against a series of contemporary drug susceptible and drug-resistant M. tuberculosis strains (minimum inhibitory concentrations (MICs) = 0.096-6.2 μM) but is inactive against nontuberculosis mycobacteria and Gram-positive and Gram-negative pathogens (MICs > 1000 μM). Complementation studies with biotin biosynthetic pathway intermediates and subsequent biochemical studies confirmed acidomycin inhibits biotin synthesis with a K_i of approximately 1 μM through the competitive inhibition of biotin synthase (BioB) and also stimulates unproductive cleavage of S-adenosyl-l-methionine (SAM) to generate the toxic metabolite 5'-deoxyadenosine. Cell studies demonstrate acidomycin selectively accumulates in M. tuberculosis providing a mechanistic basis for the observed antibacterial activity. The development of spontaneous resistance by M. tuberculosis to acidomycin was difficult, and only low-level resistance to acidomycin was observed by overexpression of BioB. Collectively, the results provide a foundation to advance acidomycin and highlight BioB as a promising target.

Molecular Basis for the N-Terminal Bromodomain-and-Extra-Terminal-Family Selectivity of a Dual Kinase-Bromodomain Inhibitor

As regulators of transcription, epigenetic proteins that interpret post-translational modifications to N-terminal histone tails are essential for maintaining cellular homeostasis. When dysregulated, "reader" proteins become drivers of disease. In the case of bromodomains, which recognize N-ε-acetylated lysine, selective inhibition of individual bromodomain-and-extra-terminal (BET)-family bromodomains has proven challenging. We describe the >55-fold N-terminal-BET bromodomain selectivity of 1,4,5-trisubstituted-imidazole dual kinase-bromodomain inhibitors. Selectivity for the BRD4 N-terminal bromodomain (BRD4(1)) over its second bromodomain (BRD4(2)) arises from the displacement of ordered waters and the conformational flexibility of lysine-141 in BRD4(1). Cellular efficacy was demonstrated via reduction of c-Myc expression, inhibition of NF-κB signaling, and suppression of IL-8 production through potential synergistic inhibition of BRD4(1) and p38α. These dual inhibitors provide a new scaffold for domain-selective inhibition of BRD4, the aberrant function of which plays a key role in cancer and inflammatory signaling.

Role and Relevance of Blood Pressure Variability in Hypertension Related Co-morbidities

Despite maintaining mean blood pressure at optimal levels, cardiovascular complications still occur in hypertensive patients. Blood pressure variability (BPV) has been implicated as a prominent factor responsible for incurring this additional risk. In this review we attempted to generate a consensus on the importance of BPV in the hypertension management and to evaluate different therapeutic options available to reduce BPV. Panel comprising of 11 leading experts from India in different areas of clinical practice (including nephrology, diabetes and endocrinology, cardiology, and critical care medicine) was convened. The board reviewed up to date literature on BPV, shared personal experiences from their clinical practice, and debated their opinions on the significance of BPV in hypertension management and also on various therapeutic options available to control it. The reviewers agreed that BPV is frequently observed in hypertensive individuals and it is a critical factor in hypertension management. Blood pressure variability can be measured by ambulatory blood pressure monitoring, home blood pressure monitoring, and office blood pressure monitoring. Members concurred that variations in blood pressure that are 10 standard deviations above the mean blood pressure should be considered as pathologically significant and such variations should be reduced using pharmacological therapies. The board opined that Angiotensin II Receptor Blockers,Calcium Channel Blockers etc such as Olmesartan, Nifedipine can be used to reduce BPV. As a way forward, the panel recommends to bridge the evidence gap that establishes a possible direct relationship between BPV and cardiovascular complications. Blood pressure variability has paramount role in the current hypertension management scenario. To reduce disease burden and increase quality of life of hypertensive individuals, physicians should consider lowering BPV along with physiological BP levels.

Specific Acetylation Patterns of H2A.Z Form Transient Interactions with the BPTF Bromodomain

Post-translational lysine acetylation of histone tails affects both chromatin accessibility and recruitment of multifunctional bromodomain-containing proteins for modulating transcription. The bromodomain- and PHD finger-containing transcription factor (BPTF) regulates transcription but has also been implicated in high gene expression levels in a variety of cancers. In this report, the histone variant H2A.Z, which replaces H2A in chromatin, is evaluated for its affinity for BPTF with a specific recognition pattern of acetylated lysine residues of the N-terminal tail region. Although BPTF immunoprecipitates H2A.Z-containing nucleosomes, a direct interaction with its bromodomain has not been reported. Using protein-observed fluorine nuclear magnetic resonance (PrOF NMR) spectroscopy, we identified a diacetylation of H2A.Z on lysine residues 4 and 11, with the highest affinity for BPTF with a Kd of 780 μM. A combination of subsequent 1H NMR Carr-Purcell-Meiboom-Gill experiments and photo-cross-linking further confirmed the specificity of the diacetylation pattern at lysines 4 and 11. Because of an adjacent PHD domain, this transient interaction may contribute to a higher-affinity bivalent interaction. Further evaluation of specificity toward a set of bromodomains, including two BET bromodomains (Brd4 and BrdT) and two Plasmodium falciparum bromodomains, resulted in one midmicromolar affinity binder, PfGCN5 (Kd = 650 μM). With these biochemical experiments, we have identified a direct interaction of histone H2A.Z with bromodomains with a specific acetylation pattern that further supports the role of H2A.Z in epigenetic regulation.

Protein-observed (19)F-NMR for fragment screening, affinity quantification and druggability assessment

NMR spectroscopy can be used to quantify the binding affinity between proteins and low-complexity molecules, termed 'fragments'; this versatile screening approach allows researchers to assess the druggability of new protein targets. Protein-observed (19)F-NMR (PrOF NMR) using (19)F-labeled amino acids generates relatively simple spectra that are able to provide dynamic structural information toward understanding protein folding and function. Changes in these spectra upon the addition of fragment molecules can be observed and quantified. This protocol describes the sequence-selective labeling of three proteins (the first bromodomains of Brd4 and BrdT, and the KIX domain of the CREB-binding protein) using commercially available fluorinated aromatic amino acids and fluorinated precursors as example applications of the method developed by our research group. Fragment-screening approaches are discussed, as well as Kd determination, ligand-efficiency calculations and druggability assessment, i.e., the ability to target these proteins using small-molecule ligands. Experiment times on the order of a few minutes and the simplicity of the NMR spectra obtained make this approach well-suited to the investigation of small- to medium-sized proteins, as well as the screening of multiple proteins in the same experiment.

Dual Screening of BPTF and Brd4 Using Protein-Observed Fluorine NMR Uncovers New Bromodomain Probe Molecules

Bromodomain-containing protein dysregulation is linked to cancer, diabetes, and inflammation. Selective inhibition of bromodomain function is a newly proposed therapeutic strategy. We describe a (19)F NMR dual screening method for small molecule discovery using fluorinated tryptophan resonances on two bromodomain-containing proteins. The chemical shift dispersion of (19)F resonances within fluorine-labeled proteins enables the simultaneous analysis of two fluorinated bromodomains by NMR. A library of 229 small molecules was screened against the first bromodomain of Brd4 and the BPTF bromodomain. We report the first small molecule selective for BPTF over Brd4, termed AU1. The Kd = 2.8 μM for AU1, which is active in a cell-based reporter assay. No binding is detected with Brd4. Three new Brd4 inhibitors with submicromolar affinity were also discovered. Brd4 hits were validated in a thermal stability assay and potency determined via fluorescence anisotropy. The speed, ease of interpretation, and low protein concentration needed for protein-observed (19)F NMR experiments in a multiprotein format offers a new method to discover and characterize selective ligands for bromodomain-containing proteins.

Fluorinated aromatic amino acids are sensitive 19F NMR probes for bromodomain-ligand interactions

We describe a ¹⁹F NMR method for detecting bromodomain–ligand interactions using fluorine-labeled aromatic amino acids due to the conservation of aromatic residues in the bromodomain binding site. We test the sensitivity, accuracy, and speed of this method with small molecule ligands (+)-JQ1, BI2536, Dinaciclib, TG101348, and acetaminophen using three bromodomains Brd4, BrdT, and BPTF. Simplified ¹⁹F NMR spectra allowed for simultaneous testing of multiple bromodomains to assess selectivity and identification of a new BPTF ligand. Fluorine labeling only modestly affected the Brd4 structure and function assessed by isothermal titration calorimetry, circular dichroism, and X-ray crystallography. The speed, ease of interpretation, and low concentration of protein needed for binding experiments affords a new method to discover and characterize both native and new ligands.

Cardio-embolic stroke due to valve tissue embolization during percutaneous transseptal mitral commissurotomy (PTMC)

Percutaneous transseptal mitral commissurotomy (PTMC) has replaced surgical commissurotomy as a treatment of choice in selected patients of rheumatic mitral stenosis. Various randomized trials have shown PTMC to be equal or superior to surgical commissurotomy in terms of hemodynamic improvement as well as long term survival. Systemic embolism is one of the dreaded complications of PTMC, which is reported in 0.5-5% of cases and involves cerebral circulation in 1% of cases. Most of the time, periprocedural embolism during PTMC is caused by the mobilization of preexisting thrombus in the left atrial appendage. We report an unusual case of acute stroke due embolization of mitral valve tissue during PTMC.

Intra-arterial thrombolysis in basilar artery occlusions combination of intra-arterial thrombolytics and Gp IIb/IIIa inhibitors in basilar artery thrombosis

Basilar artery thrombosis has high morbidity and mortality. Though intra-arterial thrombolytics have proven efficacy in the treatment of acute basilar artery occlusion, the elevation of procoagulant factors in the blood after intra-arterial thrombolysis could result in subsequent thrombus formation and clinical deterioration. Glycoprotein IIb/IIIa inhibitors have been shown to reduce this elevation in procoagulants. We present a pilot study of three cases of acute basilar artery occlusion treated with a combination of intra-arterial thrombolytics and Gp IIb/IIIa inhibitor with remarkable clinical recovery seen in all the patients.

Giant mesencephalothalamic virchow-robin spaces causing obstructive hydrocephalus. A case report

Virchow-Robin spaces accompany arteries for a variable distance into the brain substance. They are usually small but can be identified on high resolution MRI images in patients of all age groups. We report a rare case of a 40-year-old woman with giant mesencephalothalamic Virchow-Robin spaces which caused hydrocephalus requiring CSF diversion. After right ventriculoperitoneal shunt the patient recovered completely.

Heparin-induced thrombocytopenia in a case of endovascular aneurysm coiling

We report a case of 46-year-old man who underwent endovascular coil embolization for left anterior inferior cerebellar and posterior inferior cerebellar aneurysms. During embolization of both aneurysms, thrombotic complications were observed along with a relative lack of response to heparin. Intra-arterial abciximab was used to recanalize an almost completely occluded posterior inferior cerebellar artery. A marked decrease in platelet counts was found soon after embolization, which normalized within a few days. Serologic tests confirmed heparin-induced thrombocytopenia. This syndrome should be considered in cases with thromboembolic complications during endovascular procedures, particularly in patients undergoing repeated heparin exposure. A sudden decrease in platelet counts and lack of response to heparin, manifested as a relative lack of increasing activated clotting time, should make one suspect this syndrome.

Antithrombotic agents in cerebral ischaemia

The current evidence suggests that aspirin is treatment of choice when compared to anticoagulants for patients with non-cardioembolic stroke. The usefulness of combination therapy (aspirin vs. with or without warfarin) is still debated. Likewise the combination of Aspirin with clopidogrel has no added advantage (MATCH Trial). However anticoagulant therapy significantly benefits high-risk patients with atrial fibrillation in the elderly subjects whereas aspirin may still be the drug of choice in stroke prevention in low risk group in the younger age. There is dire need for well planned randomized double blind controlled studies to define the role of Antithrombotic agents in "cryptogenic stroke" (PFO/ASD related) antiphospholipid antibody syndrome, arterial dissections and intraluminal clot syndromes. Evaluation and treatment of associated risk factors in all categories needs greater emphasis.

Comprehensive stroke care: an overview

Stroke is a global epidemic and an important cause of morbidity and mortality. It ranks next to cardiovascular disease and cancer as a cause of death. "India is likely to suffer huge social and economic burden in the rehabilitation of stroke patients owing to increased life expectancy" and urbanization. Though, there are national programs in malaria eradication and tuberculosis control, there is hardly any governmental support in stroke management and rehabilitation. We propose to formulate stroke-prevention strategies specific to our national needs and covering all the age groups. Allocation of resources towards the stroke management and research is needed. Emphasis on stroke awareness in community should be stressed and should be inclusive of means of primordial and primary prevention apart from management of stroke and its recurrence. Recent international experience in stroke management has suggested the need of specialized stroke units (comprehensive stroke care under one roof). We wish to establish the need of creating awareness regarding the urgency of specialized care in acute stroke. We also wish to motivate our national health institutions to offer affordable, evidence based management of stroke and offer opportunities in stroke training and research.

Recurrent lymphocytic hypophysitis in a woman 27 years after subtotal adrenalectomy for hypercortisolism possibly of autoimmune origin

Lymphocytic hypophysitis commonly occurs in females in peripartum period but several unusual presentations have been reported. Here we report a rare case of recurrent lymphocytic hypophysitis in a woman who had subtotal adrenalectomy for hypercortisolism 27 years back. Polyglandular autoimmune endocrinopathy with an uncommon combination of Cushing's syndrome and recurrent hypophysitis is a strong possibility in this case. Treatment with steroids has been found to have beneficial effect.

Abulia: no will, no way

Abulia refers to impaired ability to perform voluntary actions, show initiative, make decisions along with decrease in movements, speech, thought and emotional reactions. We describe here two patients who developed this condition following bilateral insult to different sites in the centromedial core of the brain, the first following the cerebral venous thrombosis and the second after the right ACA and MCA infarct. Both these patients improved following treatment with Bromocriptine. These cases are described for proper identification and management by the clinicians.

Fusiform aneurysm of a persistent trigeminal artery

OBJECTIVE

Fusiform aneurysms of the persistent trigeminal artery are rare and endovascular treatment of these aneurysms has not been attempted previously. We describe a case of persistent trigeminal artery with a fusiform aneurysm in its middle third, managed using Guglielmi detachable coils (GDC).

CLINICAL PRESENTATION

A 50-year-old, diabetic and hypertensive patient presented with sudden onset headache and neck stiffness. On examination, she was conscious but disoriented, without cranial nerve or sensorimotor deficits. Four-vessel cerebral digital subtraction angiography revealed a fusiform aneurysm of the middle third of a persistent trigeminal artery on the left side with adult type posterior cerebral arteries.

INTERVENTION

Guglielmi detachable coils were used for occlusion of the persistent trigeminal artery.

RESULTS

The procedure was well tolerated but delayed ischemic neurological deficits developed due to vasospasm.

CONCLUSIONS

(1) In spite of angiographically documented independence of the anterior and posterior cerebral circulation, occlusion of a persistent trigeminal artery using endovascular techniques may result in posterior circulation stroke due to a number of factors, including occlusion of brainstem perforators taking origin from the persistent trigeminal artery or vasospasm. (2) The timing for endovascular intervention following aneurysmal rupture remains poorly defined.

Postangiographic thrombosis of a spinal arteriovenous malformation

✓ The authors report the case of a 30-year-old man who presented with progressive neurological deficits due to a spinal arteriovenous malformation (AVM). There was sudden increase in his neurological deficits after diagnostic angiography was performed. Repeated magnetic resonance imaging and angiography revealed complete thrombosis of the malformation. Stenosis in the draining vein was the most probable cause of this postangiographic occlusion of the AVM. Contrast injection during angiography may have precipitated the thrombosis.

Scalp malignant peripheral nerve sheath tumor (MPNST) with bony involvement and new bone formation: case report

Malignant peripheral nerve sheath tumors (MPNSTs) are rare neoplasms, usually arising from somatic soft tissues or peripheral nerves. Primary MPNST of the scalp is extremely rare, with only a single case reported so far. Here, we describe an unusual case of scalp MPNST in a 50-year-old male. The tumor was associated with bony projection, intracranial extension and underlying bone destruction. The tumor was treated with complete surgical excision followed by adjuvant radiotherapy. Histologically, the tumor showed malignant spindle cells with focal S-100 positivity on immunohistochemistry and a diagnosis of MPNST was made. This case is being reported for its rarity and presence of associated bony projection, which to the best of our knowledge, has not been described before in soft tissue sarcomas.

Giant intraparenchymal neurocysticercosis: unusual MRI findings

We report a case of surgically proven giant neurocysticercosis (NCC). MR imaging revealed an unusually large solitary parenchymal cystic lesion showing signal intensity similar to CSF on all pulse sequences, with internal septations and a small nodule in the anterior aspect of this lesion compatible with this diagnosis. Identification of a scolex in a cystic lesion with CSF intensity plays a key role in the diagnosis of NCC. The presence of internal septations is an atypical feature.

Malignant rhabdoid tumour of the third ventricle

A 16-year-old boy presented to the All India Institute of Medical Sciences hospital with signs and symptoms of raised intracranial pressure. A CT scan showed obstructive hydrocephalus from a large posterior third ventricle mass lesion. The patient underwent a subtotal resection of the tumour, followed by radiotherapy. Histological, ultrastructural and immunohistochemical features of the tumour were consistent with primary malignant rhabdoid tumour. The age of presentation and location of the lesion were unusual.

Cerebrotendinous xanthomatosis: neuroimaging findings in two siblings from an Indian family

Cerebrotendinous xanthomatosis (CTX) is exceptionally rare in the Indian population. We present and discuss the clinical, radiological and histopathologic findings in 2 siblings with CTX. Both the patients had juvenile cataract, mental retardation and marked cerebellar ataxia. The Achilles tendon swelling was present in only 1 patient (Case 2). MR imaging showed typical bilateral and symmetrical involvement of the dentate nuclei, inferior olives, brainstem and cerebellar hemispheric white matter. Although the diagnosis of CTX was made in the 3rd decade in both our cases, early diagnosis is possible if neuroimaging is done in the early course of the disease.

Isolated central canal rupture of spinal dermoid: report of two cases

We report two cases of lumbar spinal dermoid cysts with asymptomatic rupture and migration of free fat droplets into the central canal. No fatty droplets were seen within the lumbar subarachnoid space. The presence of fat droplets within the central canal is unusual because the central canal is rudimentary in adults. We suggest that hydromyelia secondary to tumour and specific tumour morphology might facilitate the selective rupture of dermoids into the central canal. We recommend a follow up of these patients to detect any possible intracranial migration of fat droplets and resultant complications.

Spinal cord arteriovenous fistula associated with a giant venous pouch in a three-year-old child

SUMMARY

An unusual case of direct spinal cord arteriovenous fistula (SCAVF) associated with a large venous pouch in a three-year-old child is presented. Features of this rare vascular lesion on MRI and selective angiography are described.

Post-Traumatic Cavernous Fistula Fed by Persistent Trigeminal Artery: Treatment by GDC Embolisation

SUMMARY

A case of traumatic persistent pnmltlve trigeminal artery (PPTA) cavernous sinus fistula treated with GDC embolisation is reported. Because of the small lumen of PP TA, posteriorly directed course and flow contribution from the posterior circulation, balloon embolisation via the carotid system was not considered appropriate. The fistula was successfully closed by GDC embolisation.

Partial aplasia of the posterior arch of the atlas with an isolated posterior arch remnant: findings in three cases

We report the imaging findings in three symptomatic cases of partial aplasia of the posterior arch of the atlas with an isolated posterior remnant of the arch. These cases are instructive in illustrating the mechanism of cord impingement produced by the posterior arch remnant during extension of the cervical spine. Additionally, focal increased T2 signal was observed within the cord at the level of the anomaly in two of the patients.

Transcranial Doppler evaluation of blood flow velocity changes in basal cerebral arteries in cerebral AVMs following embolisation and surgery

Blood flow velocities in the basal cerebral arteries were evaluated in 41 patients with supratentorial arteriovenous malformation (AVM), using a transcranial doppler 64-B instrument. The AVM was surgically excised in 20 patients and embolised in 21 patients. Blood flow velocities in feeding basal cerebral arteries were found markedly decreased in both the groups, at 24 hours after intervention. On follow up study at 3 months, blood flow velocity in feeding cerebral artery was found to be increased in 47 percent of patients who were embolised, but remained normal in all the patients who underwent surgery.

Newer therapeutic concept in antiplatelet aggregation inhibition--GPIIb-IIIa receptor antagonists

Numerous investigators have shown that the glycoprotein IIb/IIIa integrin mediates the final common pathway in platelet aggregation which has led to development of GP IIb/IIIa receptor antagonists. This article reviews the current status of GP IIb/IIIa receptor blockade in the management of coronary artery disease, examining the results of pivotal clinical trials.

Invasive aspergillosis presenting as a cavernous sinus mass in immuno competent individuals; report of 3 cases

Aspergillosis of the cavernous sinus is rare, especially in immuno competent individuals. We report three such cases secondary to paranasal sinus aspergillosis, with imaging findings.

Alcohol ablation of symptomatic vertebral hemangiomas

BACKGROUND AND PURPOSE

Many therapeutic techniques have been used for the treatment of symptomatic vertebral hemangiomas (SVH), and each has its own limitations. Our objective was to evaluate the therapeutic efficacy of alcohol ablation for treating these lesions.

METHODS

Fourteen patients with SVH were treated by injection of absolute alcohol into the lesion via the percutaneous transpedicular route under CT guidance. Symptoms before treatment included neurologic deficit in 13 patients and debilitating pain in one. All patients underwent preprocedural MR imaging. All patients had clinical and MR imaging follow-up (14 patients at 48-96 hours and 2 months; six at 9-15 months). Results were divided into excellent (resumption of work, alleviation of pain), good (significant improvement), and failure of treatment categories on the basis of subjective assessment of clinical improvement. Clinical improvement/deterioration was correlated with MR-revealed changes.

RESULTS

All patients showed transient deterioration of neurologic status after alcohol ablation. Subsequently, excellent results were seen in five patients and eight were in the good category. One patient in whom treatment failed also developed a complication (paravertebral abscess). Four of the eight patients with good results had preprocedural cord changes. Total follow-up ranged from 5 to 31 months, with 11 patients showing stable improvement. One patient developed recurrent hemangioma within a month. Another patient became symptomatic after initial good response, secondary to the collapse of the involved vertebral body. Good correlation was found between clinical improvement and reduction of epidural soft-tissue masses on MR images. Cord signal alteration seen on MR images in four treated patients, however, did not show any change after treatment.

CONCLUSION

Alcohol ablation is an effective management option for symptomatic vertebral hemangiomas. Although encouraging results were seen in almost 86% of our patients, a longer follow-up period still is needed to assess the stability of improvement. Potential complications include vertebral collapse and infection.

Congenital maldevelopment of intervertebral disc simulating a neurofibroma

Intervertebral disc herniation is a common cause of radiculopathy and myelopathy in adulthood. It is an uncommon tumor mimic. We report on an extradural disc associated with an osseous defect ostensibly caused by pressure erosion and appearing as a neural tumor. It showed homogeneous enhancement on a contrast-enhanced MR examination, leading to an erroneous diagnosis of nerve sheath tumor. An attempt has been made to explain the likely mechanism of formation accounting for the imaging appearances, along with a review of the literature.

Positional MRI: a technique for confirming the site of leakage in cerebrospinal fluid rhinorrhoea

We report confirmation of the site of leakage in two patients with spontaneous cerebrospinal fluid (CSF) rhinorrhoea by demonstrating CSF leaking on MRI. Both patients had midline anterior cranial fossa floor (cribriform plate/fovea ethmoidalis) dural-bone defects with arachnoid herniation with or without brain herniation into the upper part of the nasal cavity on MRI, which was subsequently confirmed surgically. Corresponding to the history of postural induction or aggravation of the rhinorrhoea, the CSF leak was demonstrated by the appearance of or increase in the sinonasal fluid collection by imaging the patient in the position of maximum leakage following initial images in the supine position.

Imaging appearance of pachymeningeal tuberculosis

OBJECTIVE

The purpose of our study was to examine imaging findings in patients with pachymeningeal tuberculosis. Imaging studies of seven patients with pachymeningeal tuberculosis were retrospectively reviewed. The diagnosis had been established on the basis of histopathology in three patients and response to antitubercular treatment in four patients.

CONCLUSION

Tuberculosis can lead to localized or diffuse involvement of the pachymeninges. Most of the focal lesions were seen as en plaque, homogeneous, uniformly enhancing, dural-based masses. The lesions appeared hyperdense on plain CT scans, isointense to brain parenchyma on T1-weighted MR images, and isointense to hypointense on T2-weighted MR images. One patient had diffuse sheet-like thickening of the pachymeninges in the right hemicranium, involving both the supratentorial and infratentorial compartments.

Idiopathic hypertrophic pachymeningitis: spectrum of the disease

Hypertrophic pachymeningitis is extremely rare. It is a fibrosing inflammatory process which involves the dura mater, including the tentorium. Numerous pathological entities produce thickening of the pachymeninges, so that idiopathic hypertrophic pachymeningitis is a diagnosis of exclusion. We describe four patients with idiopathic hypertrophic pachymeningitis who had varied clinical presentation. Imaging studies revealed diffuse thickening of the pachymeninges; in one patient there was extensive dural sinus thrombosis. Since no identifiable cause was found, the cases were labelled as idiopathic.

Intracerebral haematoma formation in herpes simplex encephalitis: a case report

Acute viral encephalitides have a high mortality and morbidity in all age groups. Early institution of appropriate medical treatment can alter the prognosis dramatically. Imaging studies may be normal or may show a wide variety of subtle findings in the initial stages. Knowledge of the extremely varied clinical as well as radiological expression of the disease is essential to enable timely diagnosis. A case is presented here of histopathologically proven Herpes simplex encephalitis (HSE), wherein a large intracerebral haematoma was seen on imaging studies. Observation of the accompanying subtle findings and knowledge of the variability of expression of this disease helped in reaching the correct diagnosis.

Role of macrophage colony-stimulating factor in atherosclerosis: studies of osteopetrotic mice

Previous in vitro and in vivo studies have suggested that macrophage colony-stimulating factor (M-CSF) plays a role in atherogenesis. To examine this hypothesis, we have studied atherogenesis in osteopetrotic (op/op) mice, which lack M-CSF due to a structural gene mutation. Atherogenesis was induced either by feeding the mice a high fat, high cholesterol diet or by crossing op mice with apolipoprotein E (apo E) knockout mice to generate mice lacking both M-CSF and apo E. In both the dietary and apo E knockout models, M-CSF deficiency resulted in significantly reduced atherogenesis. For example, in the apo E knockout model, homozygosity for the op mutation totally abolished aortic atherogenesis in male mice and reduced the size of the lesions approximately 97% in female mice. Mice heterozygous for the op mutation also exhibited a significant decrease in lesion size. Among apo E knockout mice, the frequency of atherosclerosis in aortic arch was 0/6 (op/op), 1/15 (op/+), and 12/16 (+/+). The effect of the M-CSF on atherosclerosis did not appear to be mediated by changes in plasma lipoproteins, as the op mice exhibited higher levels of atherogenic lipoprotein particles. The effects of the op mutation on atherogenesis may have resulted from decreased circulating monocytes, reduced tissue macrophages, or diminished arterial M-CSF.

MR imaging of tubercular spinal arachnoiditis

OBJECTIVE

The purpose of our study was to examine the spectrum of abnormalities seen on MR imaging in patients with tubercular spinal arachnoiditis.

MATERIALS AND METHODS

A retrospective analysis of MR findings in 22 cases of tubercular spinal arachnoiditis was carried out. The diagnosis had been established on the basis of clinical features, evidence of associated tubercular meningitis or of tubercular spondylitis, and CSF analysis.

RESULTS

Nineteen (86%) patients had involvement of more than one spinal region, with the dorsal region being most commonly involved. CSF showed increased signal intensity on T1-weighted images in 17 (77%) patients, leading to complete loss of cord-CSF interface in seven patients and shaggy cord outline in 10 patients. As suggested by increased signal intensity on T2-weighted images, we saw cord involvement in 18 (82%) patients. Three of these patients had evidence of cord cavitation. Other findings seen on unenhanced images were CSF loculations in five patients, nodules in subarachnoid space in six patients, and clumping of cauda equina nerve roots in six patients. Contrast-enhanced studies were available in 20 patients. Meningeal enhancement was seen in 16 (80%) of 20 patients, and nerve root enhancement was seen in six (30%) patients. Cord enhancement was seen in four (20%) of 20 patients. Enhancement was observed along the surface of the cord in two of these patients, whereas the other two patients showed central enhancement. Associated findings were tubercular spondylitis in two patients, basal exudate in eight patients, and intracranial granulomas in five patients.

CONCLUSION

MR imaging revealed several pathologic changes that occur in patients with tubercular spinal arachnoiditis and, hence, may play an important role in the diagnosis of this entity.

Cervical intramedullary lipoma with unusual MRI features: case report

Intramedullary (subpial) lipomas not associated with spinal dysraphism are very unusual [1]. A confident preoperative diagnosis is usually possible with MRI. We present a case of an isolated cervical intramedullary lipoma with unusual imaging morphology and imaging characteristics (distinctly low-signal on T2-weighted images) on MRI. An explanation for these features is proposed.

Transcriptional activation of the macrophage-colony stimulating factor gene by minimally modified LDL. Involvement of nuclear factor-kappa B

Minimally modified LDL (MM-LDL), obtained by mild iron oxidation or prolonged storage at 4 degrees C, has been shown to induce the expression of macrophage-colony stimulating factor (M-CSF) in cultured aortic endothelial cells. To examine whether other cell types also respond to MM-LDL, we investigated its effect on the expression of M-CSF mRNA in mouse L-cells and human aortic smooth muscle cells. Both L-cells and human aortic smooth muscle cells showed increased levels of M-CSF mRNA in response to 10 to 200 micrograms/mL MM-LDL in a dose-dependent manner. This allowed us to use mouse L-cells as a model to study the mechanism involved in MM-LDL-mediated increase in M-CSF mRNA. Nuclear runon assays showed that M-CSF gene transcription was activated by MM-LDL. In the present study, we identified specific elements that conferred MM-LDL-mediated transcriptional activation of the human M-CSF gene. Chimeric constructs containing sequential deletions in the 5'-promoter region of the M-CSF gene linked to a reporter chloramphenicol acetyltransferase (CAT) gene were transfected into mouse L-cells. The human M-CSF promoter region extending upstream from the transcription start site to nucleotide -406 showed maximum induction of CAT activity by MM-LDL. Induction of CAT activity was drastically reduced, with a deletion plasmid lacking the promoter region -406 to -344. A functional nuclear factor (NF)-kappa B binding site present in this critical region was required for MM-LDL-mediated induction of CAT activity since an internal deletion construct lacking this element showed significant loss of transcriptional activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the results of cemented, porous-ingrowth, and threaded acetabular cup fixation. A meta-analysis of the orthopaedic literature

A meta-analysis of the orthopaedic literature was performed to evaluate the clinical performance of cementless, threaded acetabular cups. The hypothesis for the study was that the clinical performance of the cementless, threaded acetabular cup is equivalent to that of the cemented and porous-ingrowth acetabular cups. Ninety-five articles were included in the study. There were 1,269 cases in the threaded cup group, 1,979 in the porous control group, and 10,230 in the cemented control group. The primary outcome variable tested was the rate of aseptic loosening of the acetabular components as measured by the revision rates following the index total hip arthroplasty procedure. Other measures of acetabular component loosening that were analyzed included clinical rating scores, pain scores, frequency of radiolucencies according to location and size, frequency of radiolucencies as a separately defined outcome variable, progressive radiolucencies, and component migration. The threaded cup group was found to have a significantly higher rate of revision, clinical and pain score failures, progressive radiolucencies and migrations when compared with the cemented and porous control groups (P < .05). Despite the many limitations of meta-analyses and the poor state of the orthopaedic literature database, this study provides a reasonable comparison of the clinical performance of threaded acetabular cups with that of cemented and porous-ingrowth acetabular cups.