Increased histone acetylation is the signature of repressed state on the genes transcribed by RNA polymerase III

Several covalent modifications are found associated with the transcriptionally active chromatin regions constituted by the genes transcribed by RNA polymerase (pol) II. Pol III-transcribed genes code for the small, stable RNA species, which participate in many cellular processes, essential for survival. Pol III transcription is repressed under most of the stress conditions by its negative regulator Maf1. We found that most of the histone acetylations increase with starvation-induced repression on several genes transcribed by the yeast pol III. On one of these genes, SNR6 (coding for the U6snRNA), a strongly positioned nucleosome in the gene upstream region plays regulatory role under repression. On this nucleosome, the changes in H3K9 and H3K14 acetylations show different dynamics. During repression, acetylation levels on H3K9 show steady increase whereas H3K14 acetylation increases with a peak at 40 min after which levels reduce. Both the levels settle by 2 hr to a level higher than the active state, which revert to normal levels with nutrient repletion. The increase in H3 acetylations is seen in the mutants reported to show reduced SNR6 transcription but not in the maf1Δ cells. This increase on a regulatory nucleosome may be part of the signaling mechanisms, which prepare cells for the stress-related quick repression as well as reactivation. The contrasting association of the histone acetylations with pol II and pol III transcription may be an important consideration to make in research studies focused on drug developments targeting histone modifications.

Structural Features of the Nucleosomal DNA Modulate the Functional Binding of a Transcription Factor and Productive Transcription

A small non-histone protein of budding yeast, Nhp6 has been reported to specifically influence the transcription of a yeast gene, SNR6. The gene is essential, transcribed by the enzyme RNA polymerase III, and codes for the U6snRNA required for mRNA splicing. A translationally positioned nucleosome on the gene body enables the assembly factor TFIIIC binding by juxtaposing its otherwise widely separated binding sites, boxes A and B. We found histone depletion results in the loss of U6 snRNA production. Changing the rotational phase of the boxes and the linear distance between them with deletions in 5 bp steps displayed a helical periodicity in transcription, which gradually reduced with incremental deletions up to 40 bp but increased on further deletions enclosing the pseudoA boxes. Nhp6 influences the transcription in a dose-dependent manner, which is modulated by its previously reported co-operator, an upstream stretch of seven T residues centered between the TATA box and transcription start site. Nhp6 occupancy on the gene in vivo goes up at least 2-fold under the repression conditions. Nhp6 absence, T₇ disruption, or shorter A–B box distance all cause the downstream initiation of transcription. The right +1 site is selected with the correct placement of TFIIIC before the transcription initiation factor TFIIIB. Thus, the T₇ sequence and Nhp6 help the assembly and placement of the transcription complex at the right position. Apart from the chromatin remodelers, the relative rotational orientation of the promoter elements in nucleosomal DNA, and Nhp6 regulate the transcription of the SNR6 gene with precision.

Regulatory networking of the three RNA polymerases helps the eukaryotic cells cope with environmental stress

Environmental stress influences the cellular physiology in multiple ways. Transcription by all the three RNA polymerases (Pols I, II, or III) in eukaryotes is a highly regulated process. With latest advances in technology, which have made many extensive genome-wide studies possible, it is increasingly recognized that all the cellular processes may be interconnected. A comprehensive view of the current research observations brings forward an interesting possibility that Pol II-associated factors may be directly involved in the regulation of expression from the Pol III-transcribed genes and vice versa, thus enabling a cross-talk between the two polymerases. An equally important cross-talk between the Pol I and Pol II/III has also been documented. Collectively, these observations lead to a change in the current perception that looks at the transcription of a set of genes transcribed by the three Pols in isolation. Emergence of an inclusive perspective underscores that all stress signals may converge on common mechanisms of transcription regulation, requiring an extensive cross-talk between the regulatory partners. Of the three RNA polymerases, Pol III turns out as the hub of these cross-talks, an essential component of the cellular stress-response under which the majority of the cellular transcriptional activity is shut down or re-aligned.

Transcription-dependent enrichment of the yeast FACT complex influences nucleosome dynamics on the RNA polymerase III-transcribed genes

The FACT (FAcilitates Chromatin Transactions) complex influences transcription initiation and enables passage of RNA polymerase (pol) II through gene body nucleosomes during elongation. In the budding yeast, ~280 non-coding RNA genes highly transcribed in vivo by pol III are found in the nucleosome-free regions bordered by positioned nucleosomes. The downstream nucleosome dynamics was found to regulate transcription via controlling the gene terminator accessibility and hence, terminator-dependent pol III recycling. As opposed to the enrichment at the 5'-ends of pol II-transcribed genes, our genome-wide mapping found transcription-dependent enrichment of the FACT subunit Spt16 near the 3'-end of all pol III-transcribed genes. Spt16 physically associates with the pol III transcription complex and shows gene-specific occupancy levels on the individual genes. On the non-tRNA pol III-transcribed genes, Spt16 facilitates transcription by reducing the nucleosome occupany on the gene body. On the tRNA genes, it maintains the position of the nucleosome at the 3' gene-end and affects transcription in gene-specific manner. Under nutritional stress, Spt16 enrichment is abolished in the gene downstream region of all pol III-transcribed genes and reciprocally changed on the induced or repressed pol II-transcribed ESR genes. Under the heat and replicative stress, its occupancy on the pol III-transcribed genes increases significantly. Our results show that Spt16 elicits a differential, gene-specific and stress-responsive dynamics, which provides a novel stress-sensor mechanism of regulating transcription against external stress. By primarily influencing the nucleosomal organization, FACT links the downstream nucleosome dynamics to transcription and environmental stress on the pol III-transcribed genes.

Diroximel fumarate to treat multiple sclerosis

On October 29, 2019, the Food and Drug Administration (FDA) of the United States approved diroximel fumarate (DRF) as an oral fumarate for the treatment of relapsing forms of multiple sclerosis. Another oral fumarate, dimethyl fumarate (DMF), was approved for the same indication on March 27, 2013. Prior to its approval, DRF did not undergo rigorous testing to determine its efficacy, as its active metabolite, monomethyl fumarate, is the same as that of DMF (bioequivalency). The efficacy, safety and tolerability of DMF have previously been demonstrated in a number of clinical trials and real-world studies. For DRF, one phase III study has been completed, and another is in progress to determine its safety, tolerability and efficacy. In this paper, we review the pharmacology, pharmacokinetics, metabolism, clinical studies and drug safety of DRF.

Interactome of the yeast RNA polymerase III transcription machinery constitutes several chromatin modifiers and regulators of the genes transcribed by RNA polymerase II

Eukaryotic transcription is a highly regulated fundamental life process. A large number of regulatory proteins and complexes, many of them with sequence-specific DNA-binding activity are known to influence transcription by RNA polymerase (pol) II with a fine precision. In comparison, only a few regulatory proteins are known for pol III, which transcribes genes encoding small, stable, non-translated RNAs. The pol III transcription is precisely regulated under various stress conditions. We used pol III transcription complex (TC) components TFIIIC (Tfc6), pol III (Rpc128) and TFIIIB (Brf1) as baits and mass spectrometry to identify their potential interactors in vivo. A large interactome constituting chromatin modifiers, regulators and factors of transcription by pol I and pol II supports the possibility of a crosstalk between the three transcription machineries. The association of proteins and complexes involved in various basic life processes like ribogenesis, RNA processing, protein folding and degradation, DNA damage response, replication and transcription underscores the possibility of the pol III TC serving as a signaling hub for communication between the transcription and other cellular physiological activities under normal growth conditions. We also found an equally large number of proteins and complexes interacting with the TC under nutrient starvation condition, of which at least 25% were non-identical under the two conditions. The data reveal the possibility of a large number of signaling cues for pol III transcription against adverse conditions, necessary for an efficient co-ordination of various cellular functions.

Improved Visualization of Cortical Lesions in Multiple Sclerosis Using 7T MP2RAGE

BACKGROUND AND PURPOSE

Cortical lesions are common and often extensive in multiple sclerosis but are difficult to visualize by MRI, leaving important questions about their clinical implications and response to therapy unanswered. Our aim was to determine whether cortical lesions are better visualized using magnetization prepared 2 rapid acquisition gradient echoes (MP2RAGE) than T2*-weighted imaging on 7T MR imaging.

MATERIALS AND METHODS

Brain MR imaging using T1-weighted MP2RAGE at 500-μm isotropic resolution, T2*-weighted gradient-echo, and T2*-weighted segmented echo-planar imaging sequences were collected for 13 patients with MS and 5 age-matched neurologically healthy controls on a 7T research system. One MS case underwent postmortem MR imaging including gradient-echo and MP2RAGE sequences, after which cortical lesions seen on MR imaging were assessed with immunohistochemistry.

RESULTS

MP2RAGE detected 203 cortical lesions (median, 16 lesions/case; interquartile range, 15), compared to 92 with T2*gradient-echo (median, 7; interquartile range, 8; P < .001) and 81 with T2*EPI (median, 7; interquartile range, 5; P < .001). This increase in lesion number detected on MP2RAGE versus T2* was observed for juxtacortical, leukocortical, and intracortical lesions. Forty-three percent of all cortical lesions were identified only on MP2RAGE. White matter lesion volume correlated with total juxtacortical (r = 0.86, P < .001) and leukocortical lesion volume (r = 0.70, P < .01) but not intracortical lesion volume, suggesting that pathophysiology may differ by lesion type. Of 4 suspected lesions seen on postmortem imaging, 3 were found to be true cortical lesions while 1 represented postmortem tissue damage.

CONCLUSIONS

A combination of MP2RAGE and T2*-weighted imaging at 7T improved detection of cortical lesions and should enable longitudinal studies to elucidate their spatiotemporal dynamics and clinical implications.

Regulation of tRNA gene transcription by the chromatin structure and nucleosome dynamics

The short, non-coding genes transcribed by the RNA polymerase (pol) III, necessary for survival of a cell, need to be repressed under the stress conditions in vivo. The pol III-transcribed genes have adopted several novel chromatin-based regulatory mechanisms to their advantage. In the budding yeast, the sub-nucleosomal size tRNA genes are found in the nucleosome-free regions, flanked by positioned nucleosomes at both the ends. With their chromosomes-wide distribution, all tRNA genes have a different chromatin context. A single nucleosome dynamics controls the accessibility of the genes for transcription. This dynamics operates under the influence of several chromatin modifiers in a gene-specific manner, giving the scope for differential regulation of even the isogenes within a tRNA gene family. The chromatin structure around the pol III-transcribed genes provides a context conducive for steady-state transcription as well as gene-specific transcriptional regulation upon signaling from the environmental cues. This article is part of a Special Issue entitled: SI: Regulation of tRNA synthesis and modification in physiological conditions and disease edited by Dr. Boguta Magdalena.

Patterns of care and outcomes for second-line targeted therapy in metastatic renal cell carcinomas: A registry based analysis

AIM

Patterns of care for metastatic renal cell carcinomas (mRCC) have seen tremendous reform in the last decade. Here, we present our pattern of care in second-line targeted therapy for mRCC.

METHODS

Patients with mRCC treated with second-line therapy were included from a prospective database. Demographics, risk stratification, and treatment details were noted. Event-free survival (EFS) and overall survival (OS) was calculated using Kaplan-Meier method. Log-rank test was used to identify factors affecting EFS and OS. Multivariate analysis was performed using cox regression.

RESULTS

Nearly 21.7% (46/212) of patients received second-line targeted treatment. Heng score for risk stratification showed 21.7% of patients in low risk, 36.9% in intermediate, and 34.8% in high risk group. Everolimus followed by pazopanib were the most common second-line therapies used in 65.2% and 13% of patients, respectively. The estimated median EFS was 3.5 months (95% confidence interval [CI] 2.7-4.26 months) and estimated median OS from the start of second-line therapy was 6.2 months (95% CI 3.4-9.0 months) with a median follow-up of 4.3 months. On univariate log-rank analysis, EFS of more than 6 months with first-line therapy was associated with improvement in EFS with second-line therapy (9.5 vs. 2.0 months; hazard ratio (HR) 0.364; P = 0.002). There was no factor independently associated with EFS or OS on multivariate analysis.

CONCLUSION

Patterns of care for second line targeted therapy tend to vary with setting. A longer EFS with first-line therapy predicts improved outcomes with second-line treatment.

Multiple nerve transfers for the reanimation of shoulder and elbow functions in irreparable C5, C6 and upper truncal lesions of the brachial plexus

In irreparable C5, C6 spinal nerve and upper truncal injuries the proximal root stumps are not available for grafting, hence repair is based on nerve transfer or neurotization. Between Feb 2004 and May 2006, 23 patients with irreparable C5, C6 or upper truncal injuries of the Brachial Plexus underwent multiple nerve transfers to restore the shoulder and elbow functions. Most of them (16 patients) sustained injury following motor cycle accidents. The average denervation period was 5.3 months. Shoulder function was restored by transfer of distal part of spinal accessory nerve to suprascapular nerve, and transfer of radial nerve branch to long head of triceps to the anterior branch of axillary nerve. Elbow function was restored by transfers of ulnar and median nerve fascicles to the biceps and brachialis motor branches of musculocutaneous nerve. All patients recovered shoulder abduction and external rotation; 7 scored M4 and 16 scored M3. Range of abduction averaged 1230(range, 800-1700). Full elbow flexion was restored in all 23 patients; 15 scored M4 and 8 scored M3. Patients with excellent results could lift 5 kgs of weight. Selective nerve transfers close to the target muscle provide an early and good return of functions. There is negligible morbidity in donor nerves. These intraplexal transfers are suitable in all cases of upper brachial plexus injuries.

In-Situ Growth of CoS Nanoparticles Onto Electrospun Graphitized Carbon Nanofibers as an Efficient Counter Electrode for Dye-Sensitized Solar Cells

One-dimensional graphitized carbon nanofibers (G-CNFs) were prepared by employing facile electrospinning technique using 10 wt% of polyacrylonitrile (PAN) solution in N,N-dimethyl formamide (DMF) as precursor followed by successive stabilization, carbonization and purification processes. Cobalt sulfide (CoS) nanoparticles were grown onto G-CNFs by hydrothermal method using cobalt chloride and L-cysteine as precursors. The results of X-ray diffraction (XRD) and Raman spectroscopy confirmed the phase formation and degree of graphitization, respectively. Field-emission scanning electron microscope (FE-SEM) and transmission electron microscope (TEM) images confirmed the morphology, growth and distribution of CoS nanoparticles over G-CNFs (CoS/G-CNFs). The electrochemical studies such as cyclic voltammetry (CV), electrochemical impedance and Tafel polarization revealed that CoS/G-CNFs have lower overpotential, low charge transfer resistance and higher exchange current density for triiodide (I− 3 reduction reaction. The superior electrocat- alytic activity of CoS/G-CNFs than std. Pt is due to combined contribution of interconnected pore structure with high surface area of G-CNFs and excellent electrocatalytic activity of CoS. In addition, the dye sensitized solar cell (DSSC) based on platinum-free CoS/G-CNFs has exhibited higher photo-conversion efficiency (PCE) under a simulated solar light irradiation of 100 mW cm−2 when compared to standard platinum (std. Pt) which is attributed to the synergistic effect of CoS with G-CNFs.

Decoding the principles underlying the frequency of association with nucleoli for RNA polymerase III-transcribed genes in budding yeast

In budding yeast, RNA polymerase III–transcribed genes preferentially associate with the nucleolar and nuclear periphery when permitted by the Rabl-like orientation of interphase chromosomes.

The association of RNA polymerase III (Pol III)–transcribed genes with nucleoli seems to be an evolutionarily conserved property of the spatial organization of eukaryotic genomes. However, recent studies of global chromosome architecture in budding yeast have challenged this view. We used live-cell imaging to determine the intranuclear positions of 13 Pol III–transcribed genes. The frequency of association with nucleolus and nuclear periphery depends on linear genomic distance from the tethering elements—centromeres or telomeres. Releasing the hold of the tethering elements by inactivating centromere attachment to the spindle pole body or changing the position of ribosomal DNA arrays resulted in the association of Pol III–transcribed genes with nucleoli. Conversely, ectopic insertion of a Pol III–transcribed gene in the vicinity of a centromere prevented its association with nucleolus. Pol III–dependent transcription was independent of the intranuclear position of the gene, but the nucleolar recruitment of Pol III–transcribed genes required active transcription. We conclude that the association of Pol III–transcribed genes with the nucleolus, when permitted by global chromosome architecture, provides nucleolar and/or nuclear peripheral anchoring points contributing locally to intranuclear chromosome organization.

Yeast Bud27 modulates the biogenesis of Rpc128 and Rpc160 subunits and the assembly of RNA polymerase III

Yeast Bud27, an unconventional prefoldin is reported to affect the expression of nutrient-responsive genes, translation initiation and assembly of the multi-subunit eukaryotic RNA polymerases (pols), at a late step. We found that Bud27 associates with pol III in active as well as repressed states. Pol III transcription and occupancy at the target genes reduce with the deletion of BUD27. It promotes the interaction of pol III with the chromatin remodeler RSC found on most of the pol III targets, and with the heat shock protein Ssa4, which helps in nuclear import of the assembled pol III. Under nutrient-starvation, Ssa4-pol III interaction increases, while pol III remains inside the nucleus. Bud27 but not Ssa4 is required for RSC-pol III interaction, which reduces under nutrient-starvation. In the bud27Δ cells, total protein level of the largest pol III subunit Rpc160 but not of Rpc128, Rpc34 and Rpc53 subunits is reduced. This is accompanied by lower transcription of RPC128 gene and lower RPC160 translation due to reduced association of mRNA with the ribosomes. The resultant alteration in the normal cellular ratio of the two largest subunits of pol III core leads to reduced association of other pol III subunits and hampers the normal assembly of pol III at an early step in the cytoplasm. Our results show that Bud27 is required in multiple activities responsible for pol III biogenesis and activity.

Composite liver tumors: a radiologic-pathologic correlation

Bi-phenotypic neoplasm refers to tumors derived from a common cancer stem cell with unique capability to differentiate histologically into two distinct tumor types. Bi-phenotypic hepatocellular carcinoma-cholangiocarcinoma (HCC-CC), although a rare tumor, is important for clinicians to recognize, since treatment options targeting both elements of the tumor are crucial. Imaging findings of bi-phenotypic HCC-CC are not specific and include features of both HCC and CC. A combination of imaging and immuno-histochemical analysis is usually needed to make the diagnosis.

Novel therapies for memory cells in autoimmune diseases

Autoimmune diseases are a major cause of morbidity, and their incidence and prevalence continue to rise. Treatments for these diseases are non-specific and result in significant adverse effects. Targeted therapies may help in improving the risk : benefit ratio associated with treatment. Immunological memory is an important feature of the vertebrate immune system that results in the production of cells that are long-lived and able to respond to antigens in a more robust manner. In the setting of autoimmunity this characteristic becomes detrimental due to the ongoing response to a self-antigen(s). These memory cells have been shown to play key roles in various autoimmune diseases such as type 1 diabetes, multiple sclerosis and psoriasis. Memory T cells and B cells can be identified based on various molecules expressed on their surface. Memory T cells can be divided into three main categories - central memory, effector memory and resident memory cells. These subsets have different proliferative potential and cytokine-producing abilities. Utilizing differentially expressed surface molecules or downstream signalling pathway proteins in these cells it is now possible to target memory cells while sparing naive cells. We will discuss the various available options for such a strategy and several potential strategies that may yield successful therapies in the future.

Cleidocranial dysplasia with autosomal dominant inheritance pattern

Cleidocranial dysplasia (CCD) is an autosomal dominant disease with a wide range of expression, characterized by clavicular hypoplasia, retarded cranial ossification, delayed bone and teeth development, supernumerary teeth, stomatognathic, craniofacial and skeletal abnormalities. This paper presents a case of CCD in a female with brachycephalic skull, depressed frontal bone and nasal bridge, hypoplastic middle one-third of face with mandibular prognathism and hyper mobility of both shoulders with associated radiographic features. Odontologist is often the first professional who patient of CCD approaches, since there is a delay in the eruption or absence of permanent teeth. The premature diagnosis allows a scope for proper treatment modalities, offering a better life quality for patient.

Systematic characterization of the conformation and dynamics of budding yeast chromosome XII

Chromosomes architecture is viewed as a key component of gene regulation, but principles of chromosomal folding remain elusive. Here we used high-throughput live cell microscopy to characterize the conformation and dynamics of the longest chromosome of Saccharomyces cerevisiae (XII). Chromosome XII carries the ribosomal DNA (rDNA) that defines the nucleolus, a major hallmark of nuclear organization. We determined intranuclear positions of 15 loci distributed every ~100 kb along the chromosome, and investigated their motion over broad time scales (0.2-400 s). Loci positions and motions, except for the rDNA, were consistent with a computational model of chromosomes based on tethered polymers and with the Rouse model from polymer physics, respectively. Furthermore, rapamycin-dependent transcriptional reprogramming of the genome only marginally affected the chromosome XII internal large-scale organization. Our comprehensive investigation of chromosome XII is thus in agreement with recent studies and models in which long-range architecture is largely determined by the physical principles of tethered polymers and volume exclusion.

A unique nucleosome arrangement, maintained actively by chromatin remodelers facilitates transcription of yeast tRNA genes

Background

RNA polymerase (pol) III transcribes a unique class of genes with intra-genic promoters and high transcriptional activity. The major contributors to the pol III transcriptome, tRNAs genes are found scattered on all chromosomes of yeast. A prototype tDNA of <150 bp length, is generally considered nucleosome-free while some pol III-transcribed genes have been shown to have nucleosome-positioning properties.

Results

Using high resolution ChIP-chip and ChIP-seq methods, we found several unique features associated with nucleosome profiles on all tRNA genes of budding yeast, not seen on nucleosome-dense counterparts in fission yeast and resting human CD4+ T cells. The nucleosome-free region (NFR) on all but three yeast tDNAs is found bordered by an upstream (US) nucleosome strongly positioned at −140 bp position and a downstream (DS) nucleosome at variable positions with respect to the gene terminator. Perturbation in this nucleosomal arrangement interferes with the tRNA production. Three different chromatin remodelers generate and maintain the NFR by targeting different gene regions. Isw1 localizes to the gene body and makes it nucleosome-depleted, Isw2 maintains periodicity in the upstream nucleosomal array, while RSC targets the downstream nucleosome. Direct communication of pol III with RSC serves as a stress-sensory mechanism for these genes. In its absence, the downstream nucleosome moves towards the gene terminator. Levels of tRNAs from different families are found to vary considerably as different pol III levels are seen even on isogenes within a family. Pol III levels show negative correlation with the nucleosome occupancies on different genes.

Conclusions

Budding yeast tRNA genes maintain an open chromatin structure, which is not due to sequence-directed nucleosome positioning or high transcription activity of genes. Unlike 5′ NFR on pol II-transcribed genes, the tDNA NFR, which facilitates tDNA transcription, results from action of chromatin remodeler Isw1, aided by Isw2 and RSC. The RSC-regulated nucleosome dynamics at the 3′ gene-end serves as a novel regulatory mechanism for pol III transcription in vivo, probably by controlling terminator-dependent facilitated recycling of pol III. Salient features of yeast tDNA chromatin structure reported in this study can explain the basis of the novel non-transcriptional roles ascribed to tDNAs.

Phase Ib study of tivozanib (AV-951) in combination with temsirolimus in patients with renal cell carcinoma

BACKGROUND

Tivozanib is a potent and selective tyrosine kinase inhibitor of vascular endothelial growth factor receptors (VEGFR)-1, -2 and -3, with a long half-life. Tivozanib has demonstrated clinical activity and acceptable tolerability in renal cell carcinoma (RCC). This phase Ib study determined the recommended phase II dose (RP2D) and evaluated the safety and clinical activity of tivozanib plus temsirolimus, a mammalian target of rapamycin inhibitor.

PATIENTS AND METHODS

Patients with advanced RCC were administered open-label tivozanib 0.5, 1.0 or 1.5mg/d orally (3 weeks on/1 week off) and temsirolimus 15 or 25 mg/week intravenously in a 3+3 dose-escalation design and subsequent expansion cohort.

RESULTS

Of 27 patients treated, 20 patients had received ≥ 1 prior VEGF-targeted therapy. No dose-limiting toxicities occurred; the RP2D was determined to be tivozanib 1.5mg/d plus temsirolimus 25mg/week. Combination of tivozanib plus temsirolimus demonstrated acceptable tolerability and suggested no synergistic toxicity. The most common grade ≤ 3 adverse events were fatigue and thrombocytopenia (15% each). One patient each required dose reduction of tivozanib or temsirolimus due to an adverse event. Confirmed partial responses and stable disease were achieved at 23% and 68%, respectively. Pharmacokinetic analyses may suggest lack of an interaction between tivozanib and temsirolimus.

CONCLUSIONS

In this small phase Ib study, tivozanib and temsirolimus were safely combined at the fully recommended dose and schedule of both agents. The observed clinical activity and manageable toxicity profile of this combination warrant further exploration in patients with RCC.

Unusual cases of foreign bodies in air passage in children

Tracheobronchial foreign bodies when not treated promptly continue to be a source of morbidity and mortality specially in the paediatric population. Chevaliar Jackson, through meticulous analysis of mechanical problems related to foreign bodies in the air and food passages and their solution, created a science of rehearsed and tested instrumental techniques for their extraction (Jackson and Jackson, 1936). They developed instruments to achieve remarkable results with an almost unbelievably low morbidity and mortality.Aspiration of foreign bodies is seen more commonly in the paediatric age group and nearly 94% of them occur in infants and children (Holinger and Holinger, 1978). According to Jackson, nearly 90% of these foreign body accidents are due to carelessness, and are therefore avoidable. We present two unusual cases of inorganic foreign bodies in the air passages in children with special reference to the problems encountered in their diagnosis and management.

Pictorial review. Hepatic vascular shunts: embryology and imaging appearances

The purpose of this pictorial review is to understand the embryological basis of the development of congenital hepatic vascular shunts and to review the multimodality imaging appearances of congenital and acquired hepatic vascular shunts. Hepatic vascular shunts are commonly seen in imaging. Familiarity with their characteristic appearances is important in order to accurately characterise these shunts and diagnose the underlying disorders.

Management strategy for facial arteriovenous malformations

Arteriovenous malformations (AVMs) are uncommon errors of vascular morphogenesis; haemodynamically, they are high-flow lesions. Approximately 50% of AVMs are located in the craniofacial region. Subtotal excision or proximal ligation of the feeding vessel frequently results in rapid progression of the AVMs. Hence, the correct treatment consists of highly selective embolisation (super-selective) followed by complete resection 24–48 hours later. We treated 20 patients with facial arteriovenous malformation by using this method. Most of the lesions (80%) were located within the cheek and lip. There were no procedure related complications and cosmetic results were excellent.

Surgical outcomes following nerve transfers in upper brachial plexus injuries

Background:

Brachial plexus injuries represent devastating injuries with a poor prognosis. Neurolysis, nerve repair, nerve grafts, nerve transfer, functioning free-muscle transfer and pedicle muscle transfer are the main surgical procedures for treating these injuries. Among these, nerve transfer or neurotization is mainly indicated in root avulsion injury.

Materials and Methods:

We analysed the results of various neurotization techniques in 20 patients (age group 20-41 years, mean 25.7 years) in terms of denervation time, recovery time and functional results. The inclusion criteria for the study included irreparable injuries to the upper roots of brachial plexus (C5, C6 and C7 roots in various combinations), surgery within 10 months of injury and a minimum follow-up period of 18 months. The average denervation period was 4.2 months. Shoulder functions were restored by transfer of spinal accessory nerve to suprascapular nerve (19 patients), and phrenic nerve to suprascapular nerve (1 patient). In 11 patients, axillary nerve was also neurotized using different donors - radial nerve branch to the long head triceps (7 patients), intercostal nerves (2 patients), and phrenic nerve with nerve graft (2 patients). Elbow flexion was restored by transfer of ulnar nerve motor fascicle to the motor branch of biceps (4 patients), both ulnar and median nerve motor fascicles to the biceps and brachialis motor nerves (10 patients), spinal accessory nerve to musculocutaneous nerve with an intervening sural nerve graft (1 patient), intercostal nerves (3rd, 4th and 5th) to musculocutaneous nerve (4 patients) and phrenic nerve to musculocutaneous nerve with an intervening graft (1 patient).

Results:

Motor and sensory recovery was assessed according to Medical Research Council (MRC) Scoring system. In shoulder abduction, five patients scored M4 and three patients M3+. Fair results were obtained in remaining 12 patients. The achieved abduction averaged 95 degrees (range, 50 - 170 degrees). Eight patients scored M4 power in elbow flexion and assessed as excellent results. Good results (M3+) were obtained in seven patients. Five patients had fair results (M2+ to M3).