Genetic ablation of Immt induces a lethal disruption of the MICOS complex

The mitochondrial contact site and cristae organizing system (MICOS) is important for crista junction formation and for maintaining inner mitochondrial membrane architecture. A key component of the MICOS complex is MIC60, which has been well studied in yeast and cell culture models. However, only one recent study has demonstrated the embryonic lethality of losing Immt (the gene encoding MIC60) expression. Tamoxifen-inducible ROSA-CreERT2-mediated deletion of Immt in adult mice disrupted the MICOS complex, increased mitochondria size, altered cristae morphology, and was lethal within 12 d. Pathologically, these mice displayed defective intestinal muscle function (paralytic ileus) culminating in dehydration. We also identified bone marrow (BM) hypocellularity in Immt-deleted mice, although BM transplants from wild-type mice did not improve survival. Altogether, this inducible mouse model demonstrates the importance of MIC60 in vivo, in both hematopoietic and non-hematopoietic tissues, and provides a valuable resource for future mechanistic investigations into the MICOS complex.

Dosimetric Impact of Seed Segmentation in GammaTile Surgically Targeted Radiation Therapy for Gliomas and Brain Metastases Cases

PURPOSE/OBJECTIVE(S)

To assess the variability of dose reporting variability due to uncertainty in segmentation of Cs-131 seeds in GammaTile therapy for gliomas and brain metastases.

MATERIALS/METHODS

Ten patients with either glioma or brain metastases had 4-11 GammaTiles placed along resection bed during craniotomy. A dose of 60 Gy is prescribed to 5 mm depth. Each GammaTile has four Cs-131 seeds imbedded in a biodegradable collagen sponge. GammaTile Post-Op workflow in MIM Symphony software is used for post-implant dose evaluation and reporting. This workflow requires a post-surgery CT to identify seeds, and a post-surgery MR for residual disease and OAR contours. Seeds are segmented using a threshold tool. Threshold levels may change depending on the CT used, thus users need to manually change the HU threshold value in each data set. Since GammaTiles are lined along the resection bed, PTVs are generated automatically by adding 8 mm expansion on the seed contours and later combined with residual disease contours. We simulate the seed contour uncertainty by applying -0.5 mm, -1.0 mm, +0.5 mm & +1.0 mm concentric margins to the current seed contours to create 4 new seed contours per patient. New PTVs are generated by adding 8 mm expansion on the new seed contours combined with residual disease contours. PTV volume, PTV volume receiving 100% and 150% of prescription dose (V100, V150), and percentage of the prescription dose received by 90% of the PTV (D90) are calculated to evaluate dose reporting variability due to seed segmentation uncertainty.

RESULTS

Mean PTV volume decreases by 8.4 cc & 10.2 cc for PTVs generated from seed contours with -0.5 mm & -1.0 mm margin, respectively, and increases by 5.8 cc & 8.2 cc, respectively, when +0.5 mm & +1 mm margins are applied to the original seed contours. We observe up to 10% change in V100 due to seed segmentation uncertainty. Mean V100 increases by 4.0% (range: 0.2% - 8.9%) & 4.9% (range: 0.5% - 11.0%) for cases with -0.5 m & -1.0 mm seed margin, respectively, and reduces by 4.2% (range: 0.5% - 6.7%) & 5.9% (range: 0.6% - 10.4%) for cases with +0.5 mm and +1.0 mm seed margin, respectively. Mean D90 increases by 7.7% (range: 4.0% - 12.6%) & 9.9% (range: 4.0% - 17.4%) for cases with -0.5 m & -1.0 mm seed margin, respectively, and reduces by 5.5% (range: 3.6% - 7.8%) & 7.4% (range: 5.2% - 9.6%) for cases with +0.5 mm and +1.0 mm seed margin, respectively. We also observe up to 8.0% changes in mean V150 when margins are applied to the seed contours.

CONCLUSION

Our results show significant impact of seed segmentation uncertainty on dose reporting in GammaTile therapy. Variability in dose reporting parameters highlight the need for a more standardized and automated approach to seed segmentation to ensure consistent and accurate dose reporting. The current manual threshold adjustment method is subject to user dependence and therefore unreliable. Development of a more robust tool could help to minimize variability and improve reliability of dose reporting.

Hong Kong Society of Clinical Blood Management recommendations for implementation of patient blood management

Patient blood management (PBM) is a patient-centred, multidisciplinary approach to optimise red cell mass, minimise blood loss, and manage tolerance to anaemia in an effort to improve patient outcomes. Well-implemented PBM improves patient outcomes and reduces demand for blood products. The multidisciplinary approach of PBM can often allow patients to avoid blood transfusions, which are associated with less favourable clinical outcomes. In Hong Kong, there has been increasing demand for blood in the ageing population, and there are simultaneous blood safety and donor issues that are adversely affecting the blood supply. To address these challenges, the Hong Kong Society of Clinical Blood Management recommends implementation of a PBM programme in Hong Kong, including strategies such as optimising red blood cell mass, improving anaemia management, minimising blood loss, and rationalising the use of blood and blood products.

Perioperative intravenous contrast administration and the incidence of acute kidney injury after major gastrointestinal surgery: prospective, multicentre cohort study

BACKGROUND

This study aimed to determine the impact of preoperative exposure to intravenous contrast for CT and the risk of developing postoperative acute kidney injury (AKI) in patients undergoing major gastrointestinal surgery.

METHODS

This prospective, multicentre cohort study included adults undergoing gastrointestinal resection, stoma reversal or liver resection. Both elective and emergency procedures were included. Preoperative exposure to intravenous contrast was defined as exposure to contrast administered for the purposes of CT up to 7 days before surgery. The primary endpoint was the rate of AKI within 7 days. Propensity score-matched models were adjusted for patient, disease and operative variables. In a sensitivity analysis, a propensity score-matched model explored the association between preoperative exposure to contrast and AKI in the first 48 h after surgery.

RESULTS

A total of 5378 patients were included across 173 centres. Overall, 1249 patients (23·2 per cent) received intravenous contrast. The overall rate of AKI within 7 days of surgery was 13·4 per cent (718 of 5378). In the propensity score-matched model, preoperative exposure to contrast was not associated with AKI within 7 days (odds ratio (OR) 0·95, 95 per cent c.i. 0·73 to 1·21; P = 0·669). The sensitivity analysis showed no association between preoperative contrast administration and AKI within 48 h after operation (OR 1·09, 0·84 to 1·41; P = 0·498).

CONCLUSION

There was no association between preoperative intravenous contrast administered for CT up to 7 days before surgery and postoperative AKI. Risk of contrast-induced nephropathy should not be used as a reason to avoid contrast-enhanced CT.

Novel lysyl oxidase inhibitors attenuate hallmarks of primary myelofibrosis in mice

Primary myelofibrosis (PMF) is a chronic myeloproliferative neoplasm (MPN) that usually portends a poor prognosis with limited therapeutic options available. Currently, only allogeneic stem cell transplantation is curative in those who are candidates, while administration of the JAK1/2 inhibitor ruxolitinib carries a risk of worsening cytopenia. The limited therapeutic options available highlight the need for the development of novel treatments for PMF. Lysyl oxidase (LOX), an enzyme vital for collagen cross-linking and extracellular matrix stiffening, has been found to be upregulated in PMF. Herein, we evaluate two novel LOX inhibitors, PXS-LOX_1 and PXS-LOX_2, in two animal models of PMF (GATA1low and JAK2V617F-mutated mice). Specifically, PXS-LOX_1 or vehicle was given to 15- to 16-week-old GATA1low mice via intraperitoneal injection at a dose of 15 mg/kg four times a week for 9 weeks. PXS-LOX_1 was found to significantly decrease the bone marrow fibrotic burden and megakaryocyte number compared to vehicle in both male and female GATA1low mice. Given these results, PXS-LOX_1 was then tested in 15- to 17-week-old JAK2V617F-mutated mice at a dose of 30 mg/kg four times a week for 8 weeks. Again, we observed a significant decrease in bone marrow fibrotic burden. PXS-LOX_2, a LOX inhibitor with improved oral bioavailability, was next evaluated in 15- to 17-week-old JAK2V617F-mutated mice at a dose of 5 mg/kg p.o. four times a week for 8 weeks. This inhibitor also resulted in a significant decrease in bone marrow fibrosis, albeit with a more pronounced amelioration in female mice. Taking these results together, PXS-LOX_1 and PXS-LOX_2 appear to be promising new candidates for the treatment of fibrosis in PMF.

Conservative management of postoperative chylous fistula with octreotide and peripheral total parenteral nutrition

Postoperative chylous fistula after neck dissection is an uncommon complication associated with significant patient morbidity. Octreotide acetate is a somatostatin analogue established in the treatment of chylothorax; however, its utility in the management of cervical chylous fistulae has not been fully evaluated. The investigators hypothesized that chylous fistula can be managed by a combination of octreotide and peripheral total parenteral nutrition (TPN). A retrospective review of cases compiled at our institution from 2009 to 2015 was conducted. Ten patients, all men, were identified as having a postoperative chylous fistula after a neck dissection. All patients were treated with peripheral TPN and intravenous octreotide. Mean age of the patients was 63.0 years (range 49 to 82). Five (50.0%) had a neck dissection for the management of metastatic nasopharyngeal carcinoma and had previous neck irradiation. In 8 (80%) patients, chylous fistula occurred in the left neck. Seven (70.0%) of the leaks occurred within the first 2 postoperative days. Eight (80%) leaks were controlled using TPN and octreotide, with 2 (20%) patients requiring surgical intervention. No factors were significant in the successful conservative management of chylous fistulae. One patient with a chylous fistula of 1,800 ml/day was managed successfully without surgical intervention. The results of this case series suggest that chylous fistulae may be managed conservatively with octreotide and TPN. However, long-term evaluation is needed to define if and when surgical intervention is required for control.

The role of extracellular matrix stiffness in megakaryocyte and platelet development and function

The extracellular matrix (ECM) is a key acellular structure in constant remodeling to provide tissue cohesion and rigidity. Deregulation of the balance between matrix deposition, degradation, and crosslinking results in fibrosis. Bone marrow fibrosis (BMF) is associated with several malignant and nonmalignant pathologies severely affecting blood cell production. BMF results from abnormal deposition of collagen fibers and enhanced lysyl oxidase-mediated ECM crosslinking within the marrow, thereby increasing marrow stiffness. Bone marrow stiffness has been recently recognized as an important regulator of blood cell development, notably by modifying the fate and differentiation process of hematopoietic or mesenchymal stem cells. This review surveys the different components of the ECM and their influence on stem cell development, with a focus on the impact of the ECM composition and stiffness on the megakaryocytic lineage in health and disease. Megakaryocyte maturation and the biogenesis of their progeny, the platelets, are thought to respond to environmental mechanical forces through a number of mechanosensors, including integrins and mechanosensitive ion channels, reviewed here.

A mass spectrometric method for quantification of tryptophan-derived uremic solutes in human serum

In addition to various physiologic roles, emerging evidence strongly points to pathogenic roles of tryptophan and of its metabolites, especially in diseases such as renal failure. Accurate estimation of levels of these metabolites in blood is important to mechanistically probe their contribution to disease pathogenesis, while clinically, such a panel can be used to risk stratify patients for a clinical phenotype. Herein, we describe a comprehensive liquid chromatography-mass spectrometry (LC/MS)-based method to determine the level of tryptophan and its metabolites (kynurenine, kynurenic acid, xanthurenic acid, anthranilic acid, indoxyl sulfate and indoxyl acetate). Human sera samples were processed through a C18 column followed by application of a binary gradient and quantitation by MS/MS. The linearity, lower limit of detection, inter- and intraassay variabilities and recovery were determined, yielding a precise, reproducible method for all the metabolites. Unlike previous studies, we further validated these methods in a well-characterized set of human sera from end stage renal disease patients compared to age-, gender- and ethnic-background matched human controls. Overall, we report an optimized LC/MS-based estimation of a comprehensive panel of tryptophan-derived metabolites with quality features within FDA standards, underscoring their readiness for translational use.

The role of the extracellular matrix in primary myelofibrosis

Primary myelofibrosis (PMF) is a myeloproliferative neoplasm that arises from clonal proliferation of hematopoietic stem cells and leads to progressive bone marrow (BM) fibrosis. While cellular mutations involved in the development of PMF have been heavily investigated, noteworthy is the important role the extracellular matrix (ECM) plays in the progression of BM fibrosis. This review surveys ECM proteins contributors of PMF, and highlights how better understanding of the control of the ECM within the BM niche may lead to combined therapeutic options in PMF.

Clustering

Clustering techniques are used to arrange genes in some natural way, that is, to organize genes into groups or clusters with similar behavior across relevant tissue samples (or cell lines). These techniques can also be applied to tissues rather than genes. Methods such as hierarchical agglomerative clustering, k-means clustering, the self-organizing map, and model-based methods have been used. Here we focus on mixtures of normals to provide a model-based clustering of tissue samples (gene signatures) and of gene profiles, including time-course gene expression data.

Papular angiolymphoid hyperplasia and lymphoplasmacytic plaque: a clinical and histological spectrum

Acral pseudolymphomatous angiokeratoma of children (APACHE) is a rare form of cutaneous pseudolymphoma characterized byangiomatous papules with a predilection for the acral regions of children. Classically, a dense dermal lymphocytic infiltrate composed of both T and B cells is seen in histological specimens, together with prominent vessels lined by plump endothelial cells. Increasing evidence suggests that this condition is neither necessarily acral, pseudolymphomatous, nor angiokeratomatous. It may not always be a pediatric disease. Therefore, the correctness of its nomenclature has been questioned. Herein, we report threecases whose clinical and histological features were consistent with the diagnosis of APACHE. To our knowledge, this is the first report of APACHE from Southeast Asia. We also discuss why we believe "APACHE" to be a misnomer and support "papular angiolymphoid hyperplasia" as a more accurate and encompassing term. In addition, we illustrate a case with significant overlapping features with lymphoplasmacytic plaque in children, suggesting that both entities may exist on a clinical andhistological spectrum.

A randomized controlled trial of 2 protocols for weaning cardiac surgical patients receiving adaptive support ventilation

PURPOSE

This study aims to compare the effectiveness of weaning with adaptive support ventilation (ASV) incorporating progressively reduced or constant target minute ventilation in the protocol in postoperative care after cardiac surgery.

MATERIAL AND METHODS

A randomized controlled unblinded study of 52 patients after elective coronary artery bypass surgery was carried out to determine whether a protocol incorporating a decremental target minute ventilation (DTMV) results in more rapid weaning of patients ventilated in ASV mode compared to a protocol incorporating a constant target minute ventilation.

RESULTS

Median duration of mechanical ventilation (145 vs 309 minutes; P = .001) and intubation (225 vs 423 minutes; P = .005) were significantly shorter in the DTMV group. There was no difference in adverse effects (42% vs 46%) or mortality (0% vs 0%) between the 2 groups.

CONCLUSIONS

Use of a DTMV protocol for postoperative ventilation of cardiac surgical patients in ASV mode results in a shorter duration of ventilation and intubation without evidence of increased risk of adverse effects.

A two-way clustering framework to identify disparities in multimorbidity patterns of mental and physical health conditions among Australians

Multimorbidity is present in more than one quarter of the population in Australia, and its prevalence increases with age. Greater multimorbidity burden among individuals is always associated with poor health-related outcomes, including quality of life, health service utilization and mortality, among others. It is thus significant to identify the heterogeneity in multimorbidity patterns in the community and determine the impact of multimorbidity on individual health outcomes. In this paper, I propose a two-way clustering framework to identify clusters of most significant non-random comorbid health conditions and disparities in multimorbidity patterns among individuals. This framework can establish a clustering-based approach to determine the association between multimorbidity patterns and health-related outcomes and to calculate a multimorbidity score for each individual. The proposed method is illustrated using simulated data and a national survey data set of mental health and wellbeing in Australia.

Suppression of adenosine 2a receptor (A2aR)-mediated adenosine signaling improves disease phenotypes in a mouse model of amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a rapidly progressing neurodegenerative disease in which the majority of upper and lower motor neurons are degenerated. Despite intensive efforts to identify drug targets and develop neuroprotective strategies, effective therapeutics for ALS remains unavailable. The identification and characterization of novel targets and pathways remain crucial in the development of ALS therapeutics. Adenosine is a major neuromodulator that actively regulates synaptic transmission. Interestingly, adenosine levels are significantly elevated in the cerebrospinal fluid (CSF) of progressing human ALS patients. In the current study, we showed that adenosine 2a receptor (A2aR), but not adenosine 1 receptor (A1R), is highly enriched in spinal (motor) neurons. A2aR expression is also selectively increased at the symptomatic onset in the spinal cords of SOD1G93A mice and end-stage human ALS spinal cords. Interestingly, we found that direct adenosine treatment is sufficient to induce embryonic stem cell-derived motor neuron (ESMN) cell death in cultures. Subsequent pharmacological inhibition and partial genetic ablation of A2aR (A2aR(+/-)) significantly protect ESMN from SOD1G93A(+) astrocyte-induced cell death and delay disease progression of SOD1G93A mice. Taken together, our results provide compelling novel evidence that A2aR-mediated adenosine signaling contributes to the selective spinal motor neuron degeneration observed in the SOD1G93A mouse model of ALS.

High throughput film dosimetry in homogeneous and heterogeneous media for a small animal irradiator

PURPOSE

We have established a high-throughput Gafchromic film dosimetry protocol for narrow kilovoltage beams in homogeneous and heterogeneous media for small-animal radiotherapy applications. The kV beam characterization is based on extensive Gafchromic film dosimetry data acquired in homogeneous and heterogeneous media. An empirical model is used for parameterization of depth and off-axis dependence of measured data.

METHODS

We have modified previously published methods of film dosimetry to suit the specific tasks of the study. Unlike film protocols used in previous studies, our protocol employs simultaneous multi-channel scanning and analysis of up to nine Gafchromic films per scan. A scanner and background correction were implemented to improve accuracy of the measurements. Measurements were taken in homogeneous and inhomogeneous phantoms at 220 kVp and a field size of 5 × 5 mm(2). The results were compared against Monte Carlo simulations.

RESULTS

Dose differences caused by variations in background signal were effectively removed by the corrections applied. Measurements in homogeneous phantoms were used to empirically characterize beam data in homogeneous and heterogeneous media. Film measurements in inhomogeneous phantoms and their empirical parameterization differed by about 2%-3%. The model differed from MC by about 1% (water, lung) to 7% (bone). Good agreement was found for measured and modelled off-axis ratios.

CONCLUSIONS

EBT2 films are a valuable tool for characterization of narrow kV beams, though care must be taken to eliminate disturbances caused by varying background signals. The usefulness of the empirical beam model in interpretation and parameterization of film data was demonstrated.

Neuronal exosomal miRNA-dependent translational regulation of astroglial glutamate transporter GLT1

Perisynaptic astrocytes express important glutamate transporters, especially excitatory amino acid transporter 2 (EAAT2, rodent analog GLT1) to regulate extracellular glutamate levels and modulate synaptic activation. In this study, we investigated an exciting new pathway, the exosome-mediated transfer of microRNA (in particular, miR-124a), in neuron-to-astrocyte signaling. Exosomes isolated from neuron-conditioned medium contain abundant microRNAs and small RNAs. These exosomes can be directly internalized into astrocytes and increase astrocyte miR-124a and GLT1 protein levels. Direct miR-124a transfection also significantly and selectively increases protein (but not mRNA) expression levels of GLT1 in cultured astrocytes. Consistent with our in vitro findings, intrastriatal injection of specific antisense against miR-124a into adult mice dramatically reduces GLT1 protein expression and glutamate uptake levels in striatum without reducing GLT1 mRNA levels. MiR-124a-mediated regulation of GLT1 expression appears to be indirect and is not mediated by its suppression of the putative GLT1 inhibitory ligand ephrinA3. Moreover, miR-124a is selectively reduced in the spinal cord tissue of end-stage SOD1 G93A mice, the mouse model of ALS. Subsequent exogenous delivery of miR-124a in vivo through stereotaxic injection significantly prevents further pathological loss of GLT1 proteins, as determined by GLT1 immunoreactivity in SOD1 G93A mice. Together, our study characterized a new neuron-to-astrocyte communication pathway and identified miRNAs that modulate GLT1 protein expression in astrocytes in vitro and in vivo.

Clustering of gene expression data via normal mixture models

There are two distinct but related clustering problems with microarray data. One problem concerns the clustering of the tissue samples (gene signatures) on the basis of the genes; the other concerns the clustering of the genes on the basis of the tissues (gene profiles). The clusters of tissues so obtained in the first problem can play a useful role in the discovery and understanding of new subclasses of diseases. The clusters of genes obtained in the second problem can be used to search for genetic pathways or groups of genes that might be regulated together. Also, in the first problem, we may wish first to summarize the information in the very large number of genes by clustering them into groups (of hyperspherical shape), which can be represented by some metagenes, such as the group sample means. We can then carry out the clustering of the tissues in terms of these metagenes. We focus here on mixtures of normals to provide a model-based clustering of tissue samples (gene signatures) and of gene profiles.

SU-E-T-163: Thin-Film Organic Photocell (OPV) Properties in MV and KV Beams for Dosimetry Applications

PURPOSE

To characterize dosimetric properties of low-cost thin film organic-based photovoltaic (OPV) cells to kV and MV x-ray beams for their usage as large area dosimeter for QA and patient safety monitoring device.

METHODS

A series of thin film OPV cells of various areas and thicknesses were irradiated with MV beams to evaluate the stability and reproducibility of their response, linearity and sensitivity to absorbed dose. The OPV response to x-rays of various linac energies were also characterized. Furthermore the practical (clinical) sensitivity of the cells was determined using IMRT sweeping gap test generated with various gap sizes. To evaluate their potential usage in the development of low cost kV imaging device, the OPV cells were irradiated with kV beam (60-120 kVp) from a fluoroscopy unit. Photocell response to the absorbed dose was characterized as a function of the organic thin film thickness and size, beam energy and exposure for kV beams as well. In addition, photocell response was determined with and without thin plastic scintillator.

RESULTS

Response of the OPV cells to the absorbed dose from kV and MV beams are stable and reproducible. The photocell response was linearly proportional to the size and about slightly decreasing with the thickness of the organic thin film, which agrees with the general performance of the photocells in visible light. The photocell response increases as a linear function of absorbed dose and x-ray energy. The sweeping gap tests performed showed that OPV cells have sufficient practical sensitivity to measured MV x-ray delivery with gap size as small as 1 mm.

CONCLUSIONS

With proper calibration, the OPV cells could be used for online radiation dose measurement for quality assurance and patient safety purposes. Their response to kV beam show promising potential in development of low cost kV radiation detection devices.

Amicrobial pustulosis associated with autoimmune disease in a patient with Sjögren syndrome and IgA nephropathy

Amicrobial pustulosis associated with autoimmune disease (APAD) is a rare clinical condition, characterized by relapsing pustular eruption, affecting mainly the skin folds. Almost all previously described cases were young women with varying underlying autoimmune diseases. We report a 36-year-old woman with the interesting triad of APAD, Sjögren syndrome and IgA nephropathy. Her rashes responded to oral prednisolone and cyclophosphamide.

Antioxidant and cytotoxicity effect of rice bran phytic acid as an anticancer agent on ovarian, breast and liver cancer cell lines

INTRODUCTION

Phytic acid (PA) has been shown to have positive nutritional benefits. There are also claims that it is able to prevent cancer through its antioxidant capability. This study investigated antioxidant activity and cytotoxic effect of PA extracted from rice bran against selected cancer cell lines (i.e. ovarian, breast and liver cancer).

METHODS

Cytotoxicity activity of PA was investigated using MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)]-2H-tetrazolium, inner salt] assay while the antioxidant activity of PA extract, commercial PA and butylated hydroxytoluene (BHT) was determined by using five different assays: ferric thiocyanate (FTC) and thiobarbituric acid (TBA) assay, beta-carotene bleaching method, DPPH radical scavenging assay and ferric reducing antioxidant power (FRAP) assay.

RESULTS

PA extracted from rice bran induced marked growth inhibition in ovary, breast and liver cancer cells with 50% growth inhibition concentration (IC50) values of 3.45, 3.78 and 1.66 mM, respectively but exhibited no sensitivity towards a normal cell line (3T3). The PA extract was also found to exert antioxidant activity when tested using the FTC, TBA, FRAP and beta-carotene bleaching methods but antioxidant activity could not be attributed to scavenging free radical species as measured by DPPH radical scavenging assay.

CONCLUSION

The PA extract from rice bran displayed safe and promising anticancer properties in selected cancer cell lines and it is believed that its antioxidant capability is the likely contributor to the observed anticancer properties.

Natural history and predictors for progression of mild childhood obstructive sleep apnoea

AIMS

The natural history of mild childhood obstructive sleep apnoea (OSA) was examined and factors associated with disease progression were identified.

METHODS

Subjects were recruited from an epidemiological study which examined the prevalence of OSA in Chinese children aged 6-13 years. The first 56 consecutive children identified with mild OSA (apnoea-hypopnoea index 1-5) were invited for a repeat assessment 2 years after the diagnosis.

RESULTS

45 children participated in the follow-up study, in 13 of whom (29%) the OSA was found to have worsened. Compared with those in whom OSA had not worsened, the worsened OSA group had a greater increase in waist circumference, a higher prevalence of large tonsils (occupying > or =50% of the airway) at both baseline and follow-up, and a higher prevalence of habitual snoring at both baseline and follow-up. The presence of large tonsils had a positive predictive value of 53% and a negative predictive value of 83% for worsening OSA over a 2-year period. Multivariate linear regression analysis showed that the change in obstructive apnoea-hypopnoea index was associated with age at baseline (beta (SE) = -0.92 (0.34), p = 0.009), gender (male = 1; female = 0) (beta (SE) = 4.69 (1.29), p<0.001), presence of large tonsils at baseline (beta (SE) = 4.36 (1.24), p = 0.001), change in waist circumference (beta (SE) = 0.30 (0.09), p = 0.002) and persistently large tonsils (beta (SE) = 5.69 (1.36), p<0.001) over the 2-year period.

CONCLUSIONS

Mild OSA in the majority of children does not resolve spontaneously. Subjects with tonsillar hypertrophy, especially boys, should be closely monitored to allow early detection of worsening OSA. Weight control should be stressed in the management of childhood OSA.

A tether for Woronin body inheritance is associated with evolutionary variation in organelle positioning

Eukaryotic organelles evolve to support the lifestyle of evolutionarily related organisms. In the fungi, filamentous Ascomycetes possess dense-core organelles called Woronin bodies (WBs). These organelles originate from peroxisomes and perform an adaptive function to seal septal pores in response to cellular wounding. Here, we identify Leashin, an organellar tether required for WB inheritance, and associate it with evolutionary variation in the subcellular pattern of WB distribution. In Neurospora, the leashin (lah) locus encodes two related adjacent genes. N-terminal sequences of LAH-1 bind WBs via the WB–specific membrane protein WSC, and C-terminal sequences are required for WB inheritance by cell cortex association. LAH-2 is localized to the hyphal apex and septal pore rim and plays a role in colonial growth. In most species, WBs are tethered directly to the pore rim, however, Neurospora and relatives have evolved a delocalized pattern of cortex association. Using a new method for the construction of chromosomally encoded fusion proteins, marker fusion tagging (MFT), we show that a LAH-1/LAH-2 fusion can reproduce the ancestral pattern in Neurospora. Our results identify the link between the WB and cell cortex and suggest that splitting of leashin played a key role in the adaptive evolution of organelle localization.

In the kingdom Fungi, tubular cells called hyphae grow by tip extension and lateral branching to produce an interconnected multicellular syncytium and this unique cellular architecture is especially suited to foraging, long distance transport, and invasive growth. Major groups of fungi have independently evolved cellular organelles that support this form of multicellularity. Woronin bodies evolved over 400 million years ago in the common ancestor of filamentous Ascomycetes and perform an adaptive function to seal pores that connect hyphal compartments (septal pores) in response to cellular wounding. This study identifies Leashin, a tethering protein that promotes equitable Woronin body inheritance by providing a link to the cell cortex. Patterns of cortex association display systematic variation; in most of the filamentous Ascomycetes, Woronin bodies are tethered to the septal pore. By contrast, a delocalized pattern has recently evolved in a group represented by Neurospora and Sordaria. We present evidence suggesting that the ancestral leashin gene was split into two independent transcription units to permit this evolutionary transition. This work is exemplary of how filamentous Ascomycetes with well-resolved phylogenetic relationships, diverse sequenced genomes and powerful haploid genetics provide model systems for understanding evolutionary innovation within a functional cellular and physiological context.

Making two organelles from one: Woronin body biogenesis by peroxisomal protein sorting

Woronin bodies (WBs) are dense-core organelles that are found exclusively in filamentous fungi and that seal the septal pore in response to wounding. These organelles consist of a membrane-bound protein matrix comprised of the HEX protein and, although they form from peroxisomes, their biogenesis is poorly understood. In Neurospora crassa, we identify Woronin sorting complex (WSC), a PMP22/MPV17-related membrane protein with dual functions in WB biogenesis. WSC localizes to large peroxisome membranes where it self-assembles into detergent-resistant oligomers that envelop HEX assemblies, producing asymmetrical nascent WBs. In a reaction requiring WSC, these structures are delivered to the cell cortex, which permits partitioning of the nascent WB and WB inheritance. Our findings suggest that WSC and HEX collaborate and control distinct aspects of WB biogenesis and that cortical association depends on WSC, which in turn depends on HEX. This dependency helps order events across the organellar membrane, permitting the peroxisome to produce a second organelle with a distinct composition and intracellular distribution.

Management of Retrosternal Goitre with Superior Vena Cava Obstruction

Acute respiratory and cardiovascular decompensation secondary to retrosternal goitre is uncommon but life threatening. We report our experience of successful surgical management of a patient who presented acute enlargement of the mediastinal component of retrosternal goitre, which resulted in tracheal and vena cava compression.

Sweet's syndrome: a spectrum of unusual clinical presentations and associations

BACKGROUND

Sweet's syndrome (SS) is the prototypic neutrophilic dermatosis. First described in 1964, the characterization of new clinical associations, unique histopathological findings and clinical variants have stimulated much interest and discussion recently. However, the prevalence of these unusual variants and clinical associations within a single cohort of patients, has not been described.

OBJECTIVES

To describe and evaluate the prevalence of unusual clinical and histopathological features, as well as the clinical associations of SS seen in patients from the National Skin Centre, Singapore.

METHODS

This is a retrospective study of all consecutive cases of SS seen at our centre over a 5.5-year period (June 1999-December 2004). Data on associated systemic diseases was obtained from the medical records and matched with information from the National Cancer Registry, Singapore. Patients not actively followed up for more than 3 months were contacted for their updated health status.

RESULTS

Thirty-seven patients were identified. Ten (27%) had non-idiopathic SS. These were associated with haematological disorders, connective tissue disorders, infections or a drug. Twenty-nine patients (78%) had at least one atypical clinical or histopathological feature. Atypical clinical features included bullous lesions, SS with hand involvement or neutrophilic dermatoses of the hands and the concomitant existence of subcutaneous SS with pyoderma gangrenosum. SS was the presenting feature in three patients with infections caused by atypical organisms, including Mycobacterium chelonae, Penicillium species and Salmonella type D. Unique histopathological variants included subcutaneous SS and lesions containing an admixture of mature and immature neutrophils. Subcutaneous neutrophilic inflammation seemed to be more common in patients with an underlying haematological disorder. This group of patients also had a lower mean haemoglobin level.

CONCLUSIONS

Unusual clinical and histopathological variants of SS described in the literature are similarly encountered in our cohort of patients, with some features being more common than others. We highlight and discuss some unique clinical and histopathological observations seen in our patients with SS.

A mixture model with random-effects components for clustering correlated gene-expression profiles

MOTIVATION

The clustering of gene profiles across some experimental conditions of interest contributes significantly to the elucidation of unknown gene function, the validation of gene discoveries and the interpretation of biological processes. However, this clustering problem is not straightforward as the profiles of the genes are not all independently distributed and the expression levels may have been obtained from an experimental design involving replicated arrays. Ignoring the dependence between the gene profiles and the structure of the replicated data can result in important sources of variability in the experiments being overlooked in the analysis, with the consequent possibility of misleading inferences being made. We propose a random-effects model that provides a unified approach to the clustering of genes with correlated expression levels measured in a wide variety of experimental situations. Our model is an extension of the normal mixture model to account for the correlations between the gene profiles and to enable covariate information to be incorporated into the clustering process. Hence the model is applicable to longitudinal studies with or without replication, for example, time-course experiments by using time as a covariate, and to cross-sectional experiments by using categorical covariates to represent the different experimental classes.

RESULTS

We show that our random-effects model can be fitted by maximum likelihood via the EM algorithm for which the E(expectation)and M(maximization) steps can be implemented in closed form. Hence our model can be fitted deterministically without the need for time-consuming Monte Carlo approximations. The effectiveness of our model-based procedure for the clustering of correlated gene profiles is demonstrated on three real datasets, representing typical microarray experimental designs, covering time-course, repeated-measurement and cross-sectional data. In these examples, relevant clusters of the genes are obtained, which are supported by existing gene-function annotation. A synthetic dataset is considered too.

AVAILABILITY

A Fortran program blue called EMMIX-WIRE (EM-based MIXture analysis WIth Random Effects) is available on request from the corresponding author.

Autosomal dominant familial chronic mucocutaneous candidiasis associated with acne rosacea

INTRODUCTION

Autosomal dominant chronic mucocutaneous candidiasis (CMC) without endocrinopathy (OMIM 114580) is a well-described entity. The associations recorded with this disorder to date are intercellular adhesion molecule-1 (ICAM-1) deficiency and hyper-immunoglobulin E syndrome.

CLINICAL PICTURE

We report a new association in a family (mother and nonidentical twin sons) where acne rosacea is a prominent feature together with CMC. In addition, antibodies to thyroid microsomal and antiparietal cell were also isolated. The autoantibodies might be associated with a current "latent" endocrinopathy in particular autoimmune thyroiditis.

TREATMENT

The patient was treated with intermittent pulses of itraconazole for the candidiasis and doxycycline initially before being substituted with isotretinoin 6 months later for the rosacea.

OUTCOME

The patient's candidiasis responded well and has been in remission for 3 months while his rosacea continues to improve.

Does the Presence of a Tracheal Bronchus Affect the Margin of Safety of Double-Lumen Tube Placement?

During double-lumen tube (DLT) placement, the anesthesiologist must be mindful of the margin of safety. We determined how this margin is affected by the presence of a tracheal bronchus by elucidating the mathematical relationship between some relevant physical dimensions of the trachea, bronchi, and DLT. Our results suggest that a tracheal bronchus only rarely affects the intrinsic margin of safety of DLT placement. When the tracheal bronchus is located much higher than its most frequently seen location (within 2 cm from the carina), however, there is increased risk that it could be blocked by the tracheal cuff of a left-sided DLT.

Cutaneous Mycobacterium haemophilum infections in immunocompromised patients in a dermatology clinic in Singapore

INTRODUCTION

Mycobacterium haemophilum, a nontuberculous mycobacterium (NTM) that was first described in 1978, is a pathogen that can cause an array of symptoms in immunocompromised patients, predominantly cutaneous.

CLINICAL PICTURE

We report our hospital's experience with the first 3 patients diagnosed with this infection from 1994 to 2002. All were women; one had systemic lupus erythematosus (SLE), one had mycosis fungoides and the last had Sjogren's syndrome with recurrent bacterial infections, although the specific nature of her immunocompromised state has not been defined. All were HIV negative. All 3 women presented with cutaneous lesions--the first with recurrent erythematous plaques on the limbs and back, the second with tender nodules and abscesses on the knees, and the third with papular eruptions on the cheek.

TREATMENT/OUTCOME

All responded to a combination of antibiotics and are presently still undergoing treatment and follow-up.

CONCLUSION

Infections caused by M. haemophilum occur mainly in immunocompromised patients. They can present with a variety of cutaneous manifestations, which require a high index of suspicion and coordination between the treating physician and the laboratory for diagnosis. Combination antibiotic treatment is recommended, and patients should be followed up after treatment to survey for possible relapse.

A case of nephrogenic fibrosing dermopathy

INTRODUCTION

Nephrogenic fibrosing dermopathy is a recently recognised fibrosing disorder originally identified as a scleromyxoedema-like cutaneous disease in patients with renal disease.

CLINICAL PICTURE

A 45-year-old lady with systemic lupus erythematosus presented with well-defined erythematous, non-tender, indurated plaques on both legs 4 months after haemodialysis for rapidly progressive glomerulonephritis and acute renal failure. Skin biopsy showed dermal fibrosis with increased proliferation of dermal fibroblasts and collagen bundles separated by clefts. There were increased dermal deposits of mucin and an increase in elastic fibres.

TREATMENT AND OUTCOME

Haemodialysis was instituted for 2 weeks followed by monthly intravenous cyclophosphamide. Skin lesions remained unchanged 8 months later despite normalisation of renal function.

CONCLUSION

Nephrogenic fibrosing dermopathy appears to be a definite new entity in patients with underlying renal insufficiency. Further multi-centre collaborative study is necessary to identify the prevalence, cause, treatment and prognosis of this disorder.

Discovery of binding motif pairs from protein complex structural data and protein interaction sequence data

Unravelling the underlying mechanisms of protein interactions requires knowledge about the interactions' binding sites. In this paper, we use a novel concept, binding motif pairs, to describe binding sites. A binding motif pair consists of two motifs each derived from one side of the binding protein sequences. The discovery is a directed approach that uses a combination of two data sources: 3-D structures of protein complexes and sequences of interacting proteins. We first extract maximal contact segment pairs from the protein complexes' structural data. We then use these segment pairs as templates to sub-group the interacting protein sequence dataset, and conduct an iterative refinement to derive significant binding motif pairs. This combination approach is efficient in handling large datasets of protein interactions. From a dataset of 78,390 protein interactions, we have discovered 896 significant binding motif pairs. The discovered motif pairs include many novel motif pairs as well as motifs that agree well with experimentally validated patterns in the literature.

Modelling the distribution of ischaemic stroke-specific survival time using an EM-based mixture approach with random effects adjustment

A two-component survival mixture model is proposed to analyse a set of ischaemic stroke-specific mortality data. The survival experience of stroke patients after index stroke may be described by a subpopulation of patients in the acute condition and another subpopulation of patients in the chronic phase. To adjust for the inherent correlation of observations due to random hospital effects, a mixture model of two survival functions with random effects is formulated. Assuming a Weibull hazard in both components, an EM algorithm is developed for the estimation of fixed effect parameters and variance components. A simulation study is conducted to assess the performance of the two-component survival mixture model estimators. Simulation results confirm the applicability of the proposed model in a small sample setting.

A case of penicillamine-induced dermopathy

INTRODUCTION

We describe an interesting patient with penicillamine-induced dermopathy.

CLINICAL PICTURE

A 49-year-old woman presented with a 1-year history of recurrent haemorrhagic blisters, milia and purpura over both her elbows, while on long-term penicillamine therapy (1.5 g daily) for Wilson's disease. Histologically, dermal elastin fibres were markedly reduced in the affected areas, consistent with penicillamine-induced elastolysis.

TREATMENT AND OUTCOME

The patient's lesions improved significantly after reduction of her penicillamine dose to 500 mg daily.

CONCLUSIONS

The cutaneous side effects of long-term penicillamine therapy are important to recognise as they may be associated with significant morbidity and may be markers of more ominous underlying systemic elastic fibre damage.

Treatment of toxic epidermal necrolysis in AIDS with intravenous immunoglobulins

Individuals with AIDS are at higher risk of developing severe cutaneous adverse drug reactions. We report two AIDS patients with drug-induced toxic epidermal necrolysis (TEN). The suspected drugs were discontinued. Both patients were treated with intravenous human immunoglobulins at a dose of 1 g/kg body weight per day for two consecutive days and both experienced a good outcome. Intravenous immunoglobulin potentially lowers the morbidity and mortality of TEN and shortens the duration of the patient's hospitalization.