Immediate food hypersensitivity among adults attending a clinical immunology/allergy centre in Singapore

INTRODUCTION

The patient characteristics, clinical features and causative foods in 74 consecutive adult patients with immediate food hypersensitivity were studied.

METHODS

A retrospective review of 74 consecutive adults who presented during the study period from July 1, 1994 to April 30, 2002 was performed.

RESULTS

There were 35 male and 39 female patients, with a mean age of 36.3 +/- 10.9 (range, 19-66) years. The most common causative foods were seafood crustaceans, molluscs and bird's nest. Prawn and crab were the most commonly implicated crustacean, and limpet the commonest culprit mollusc. The main symptoms were periorbital angioedema (64.9 percent), dyspnoea/wheezing (44.6 percent) and urticaria (44.6 percent). 66 percent of the patients developed anaphylaxis. 34 (45.9 percent) had concomitant allergic rhinoconjunctivitis, asthma, eczema or combinations of these atopic diseases. Only six (8.1 percent) patients had a family history of food allergy. Skin prick tests (SPT) to commercially-prepared food allergens were positive in 22 of 36 patients (61.1 percent) tested. SPT to the fresh, cooked or canned food products were positive in 11 of 20 (55 percent) cases where the food allergen was not commercially available. Open food challenges were required for diagnosis in two patients who had negative SPT.

CONCLUSION

The most common food allergens in our patients were seafood crustaceans, molluscs and bird's nest. More than half of the patients had concomitant allergic rhinitis, asthma and/or eczema. The pattern of food allergy in Singapore differs from Caucasian populations, likely to be because of different regional dietary patterns and methods of food preparation.

Image deconvolution in spherical aberration-corrected high-resolution transmission electron microscopy

The method of image deconvolution developed previously for FEG high-resolution transmission electron microscope (HRTEM) without a spherical aberration (C(s)) corrector was for the first time applied to FEG HRTEM with a C(s)-corrector. The principle and the procedure of image deconvolution are briefly described. Four qualified [1 1 0] images of Si were selected from a through-focus series to perform image deconvolution. The projected potential is successfully derived from all the images, and the obtained "dumbbell" structure maps of Si [1 1 0] are in good agreement with the calculated potential map. The criterion of selecting qualified images for performing image deconvolution is indicated. The possibility of applying image deconvolution to defect study and to ab initio crystal structure determination is discussed.

Anaphylaxis in adults referred to a clinical immunology/allergy centre in Singapore

INTRODUCTION

To study the clinical features and causes of anaphylaxis in consecutive adult patients referred to a clinical immunology/allergy centre in Singapore.

METHODS

A retrospective review of 67 consecutive adults with anaphylaxis who presented from July 1, 1998 to February 28, 2002 was performed. Anaphylaxis was defined as a severe life-threatening systemic IgE-mediated hypersensitivity reaction. Non-steroidal anti-inflammatory drug-induced idiosyncratic reactions and other non-IgE mediated reactions were excluded. Hypotension and bronchospasm were not required to make a diagnosis. The aetiology was determined from clinical history followed by measurement of allergen-specific IgE levels, skin prick test with commercially-available allergen extracts or prick-prick test with the fresh/cooked/canned food products.

RESULTS

The mean age of patients was 32.9 +/- 10.9 (range 19-57) years. There were 44 (65.7 percent) males and 23 (34.3 percent) females. The main causes were food (44.8 percent), insect stings (32.8 percent) and idiopathic (22.4 percent). There were no cases due to drugs or natural rubber latex. Seafood (crustaceans and molluscs) comprised 66.7 percent of food-induced anaphylaxis. Honeybee and wasp stings together comprised 45 percent of insect venom anaphylaxis. The most common manifestations were dyspnoea (59.7 percent), urticaria (58.2 percent), angioedema (44.8 percent), and syncope (43.3 percent). Hypotension was documented in only 28.4 percent of cases.

CONCLUSION

Food (crustaceans and molluscs) was the most common cause followed by insect stings or bites. The inability to identify the causative insect in 50 percent of cases with insect venom anaphylaxis limited the role of specific immunotherapy. Compared to other reported series, there were no cases of drug or latex anaphylaxis.

Why generic and disease-specific quality-of-life instruments should be used together for the evaluation of patients with persistent allergic rhinitis

BACKGROUND

The importance of assessing health-related quality of life (HRQL) of patients with allergic rhinitis (AR) has been well established, but the specific roles of rhinitis-specific or general health instruments have not been delineated.

OBJECTIVE

We analysed the psychometric properties of a disease-specific instrument, the Rhinoconjunctivitis Quality-of-Life Questionnaire (RQLQ) and the general health instrument, the Medical Outcome Short-Form 36 (SF-36) as they are employed in combination in patients with persistent AR in clinical practice.

METHOD

We analysed the data collected from a prospective study of 43 newly diagnosed patients with persistent AR and 44 controls. We interviewed the patients four times, at baseline, weeks 4, 8 and 10.

RESULTS

The RQLQ and SF-36 have good discriminative property, internal consistency, and test-retest reliability. The RQLQ is superior to the SF-36 as an evaluative instrument because more of its domains respond to change, the magnitude of change was greater, and the response was faster. The SF-36 is more susceptible to floor and ceiling effects. Both instruments are unsuitable for mildly symptomatic patients based on Rasch model analysis. Each questionnaire assesses a distinct and significant portion of the total HRQL of persistent AR.

CONCLUSION

The SF-36 and RQLQ are good for discriminating rhinitis patients from controls, but the former is poor for detecting changes in QOL. Both are inappropriate for mildly symptomatic patients. Each instrument measures non-overlapping halves of the measurable HRQL. For an assessment of the HRQL in persistent AR that is complete and responsive both instruments should be employed together.

Modeling of muscle fatigue using Hill's model

A new model incorporating muscle fatigue has been developed to predict the effect of muscle fatigue on the force-time relationship of skeletal muscle by using the PAK-program. Differential equations in the incremental form have been implemented into Hill's muscle model. In order to describe the effect of muscle fatigue and recovery on skeletal muscle behaviors, a set of equations in terms of three phenomenological parameters which are a fatigue curve under sustained maximal activation, a recovery curve and an endurance function were developed. With reference to existing models and experimental results, the input parameters for fatigue curve under sustained maximal activation and endurance function were determined. The model has been investigated under an isometric condition. The effects of different shapes of the recovery curves have also been considered in this model. Validation of the model has been performed by comparing the predicted results with the experimental data from an existing literature.

Influence of interphase layer on the overall elasto-plastic behaviors of HA/PEEK biocomposite

A three-dimensional finite element unit cell model has been designed and constructed for studying mechanical properties of hydroxyapatite (HA) reinforced polyetheretherketone (PEEK) biocomposite. The model consists of an elastic-brittle HA spherical particle, an elasto-plastic matrix and an interphase layer between the particle and the matrix. The interphase layers with four different kinds of material behaviors have been taken into consideration to examine their effects on the overall properties of the composite. The damage evolution in the matrix and the interphase layer, and the interface failure, were also taken into account. Some other factors, such as mesh sensitivity, loading velocity and mass scale scheme, were also discussed in this investigation. A general-purpose finite element software package, ABAQUS, incorporated with a user-defined material subroutine, was used to perform the analysis. The predicted results were compared with the experimental data obtained from existing literatures. The results predicted by using the cell model with consideration of the matrix degradation and the effects of the damage and failure on the interphase layer are in good agreement with the experimental ones. Hence, the suitability of our proposed cell model incorporated with an appropriate type of the interphase layer for modeling the mechanical properties of the particulate biocomposite could be verified.

Active finite element analysis of skeletal muscle-tendon complex during isometric, shortening and lengthening contraction

An active finite element model was developed to predict the mechanical behaviors of skeletal muscle-tendon complex during isometric, shortening and lengthening contraction. The active finite element was created through incorporation of a user-defined material property into ABAQUS finite element code. The active finite element is controlled by a motor element that is activated by a mathematical function. The nonlinear passive behavior of the muscle was defined by the viscoelastic elements and can be easily altered to other properties by using other elements in the material library without the need of re-defining the constitutive relation of the muscle. The isometric force-length relationship, force-strain relations of the muscle-tendon complex during both shortening and lengthening contraction and muscle relaxation response were predicted using the proposed finite element model. The predicted results were found to be in good agreement with available experimental data. In addition, the stress distribution in the muscle-tendon complex during isometric, shortening and lengthening contractions was simulated. The location of the maximum stress may provide useful information for studying muscle damage and fatigue in the future.

Neuroactive steroids reduce neuronal excitability by selectively enhancing tonic inhibition mediated by delta subunit-containing GABAA receptors

Neuroactive steroids are potent modulators of gamma-aminobutyric acid type A receptors (GABAARs), and their behavioral effects are generally viewed in terms of altered inhibitory synaptic transmission. Here we report that, at concentrations known to occur in vivo, neuroactive steroids specifically enhance a tonic inhibitory conductance in central neurons that is mediated by extrasynaptic delta subunit-containing GABAARs. The neurosteroid-induced augmentation of this tonic conductance decreases neuronal excitability. Fluctuations in the circulating concentrations of endogenous neuroactive steroids have been implicated in the genesis of premenstrual syndrome, postpartum depression, and other anxiety disorders. Recognition that delta subunit-containing GABAARs responsible for a tonic conductance are a preferential target for neuroactive steroids may lead to novel pharmacological approaches for the treatment of these common conditions.

Wear performance of ultrahigh molecular weight polyethylene/quartz composites

Ultrahigh molecular weight polyethylene (UHMWPE)/quartz composites were compression molded in the presence of organosiloxane, and then hydrolyzed. The used organosiloxane is vinyl tri-ethyloxyl silane. The gelation, the melting behavior, the crystallinity, the mechanical properties and the wear resistance of UHMWPE/quartz composites were investigated. The results showed that organosiloxane can act as a cross-linking agent for UHMWPE matrix and serve as a coupling agent for improving the bonding between the quartz particles and the UHMWPE matrix. The correlation between the various properties and the morphology of the composites has been discussed. At about 0.5phr organsiloxane while the degree of crystallinity of the composite is at the peak value of 57%, the mechanical properties and the wear resistance of UHMWPE/quartz composites reaches their maximum.

Cyclophosphamide type I hypersensitivity in systemic lupus erythematosus

Cyclophosphamide is an important immunosuppressive agent in the treatment of many rheumatic diseases. Urticaria and anaphylaxis to intravenous cyclophosphamide (i.v. CYC) have been reported in patients with haematological and solid organ malignancies. This is the first report in the rheumatology literature of a type I hypersensitivity reaction following monthly i.v. CYC. An 18-year-old girl with systemic lupus erythematosus (SLE) developed generalized urticaria (without concomitant angioedema or anaphylaxis) following i.v. CYC. She had previously developed life-threatening angioedema following a respiratory tract infection. She successfully completed regular pulse i.v. CYC with pre-medication with anti-histamine. In the absence of a severe type I hypersensitivity reaction and other suitable immunosuppressive agents, i.v. CYC may be safely continued with pre-medication and careful monitoring during each infusion.

Enhanced wear performance of ultra high molecular weight polyethylene crosslinked by organosilane

Ultra high molecular weight polyethylene (UHMWPE) crosslinked by organosilane was thermal compression molded. The organosilane used was the tri-ethyloxyl vinyl silane. Its gelation, melting behavior, crystallinity, mechanical and wear-resisting properties were systematically investigated. The results showed that the gel ratio of UHMWPE increases with the incorporation of organosilane. At a low content of organosilane, the melting point and crystallinity of the crosslinked UHMWPE increase, and hence the mechanical and wear-resisting properties are improved. However, at a high content of organosilane, these performances of the crosslinked UHMWPE become worse. At 0.4 phr silane, the wear resistance of crosslinked UHMWPE reaches its optimum value.

Reconstruction of shoulder function using a reflected long head biceps: a moment arm study

A tendon transfer technique is proposed for the reconstruction of the paralyzed shoulders secondary to brachial plexus injury. This innovative technique does not require bone-to-bone or tendon to-bone fixation, and attempts to overcome other clinical limitations such as those due to insufficient length of donor muscle. The approach is referred to as the reflected long head biceps (RLHB) technique. The long head of biceps tendons is utilized as a bridging tendon graft. Two surgical alternatives, namely the through-deltoid (TD) pathway and the sub-deltoid (SD) pathway, were studied. The moment arms of the transferred tendons were assessed and reported. The TD technique yielded a larger moment than the SD technique. In the plane 30 degrees anterior to the scapular plane, the average moment arms were 3.8cm TD and 3.0cm SD at zero elevation. Such differences tended to further widen with increasing elevation. At 80 degrees elevation, the moment arms became 3.2cm TD and 1.2cm SD. The results supported the clinical feasibility of this RLHB tendon transfer approach.

Hollow spheres of MCM-41 aluminosilicate with pinholes

Hollow spheres of MCM-41 mesoporous aluminosilicates, with two small holes on the shell, have been synthesized from a surfactant-aluminosilicate gel composite.

Thalamic activation during an attention-to-prepulse startle modification paradigm: a functional MRI study

BACKGROUND

Prepulse inhibition (PPI) of the startle reflex reflects early stages of information processing and is modulated by selective attention. Animal models indicate medial frontal-thalamic circuitry is important in PPI modulation. We report data from the first functional magnetic resonance imaging (fMRI) study examining whether attending to or ignoring a prepulse differentially activates brain areas within this circuitry.

METHODS

Ten healthy subjects received structural and functional MRI. During fMRI acquisition, subjects heard intermixed attended and ignored tones serving as prepulses to the startle stimulus. Regions of interest were traced on structural MRI and coregistered to fMRI images.

RESULTS

Greater amplitude fMRI blood-oxygen-level-dependent response to attended than ignored PPI conditions occurred in the right thalamus, and bilaterally in the anterior and mediodorsal thalamic nuclei, whereas the startle-alone condition showed deactivation. In transitional medial cortex (Brodmann Area 32), which is involved in affective processing of noxious stimuli, the startle-alone condition elicited the greatest response, the attended-PPI condition showed the smallest response, and the ignored-PPI condition was intermediate.

CONCLUSIONS

These findings extend animal models to humans by indicating thalamic involvement in the modulation of PPI. Further fMRI investigations may elucidate other key structures in the circuitry underlying normal and disordered modulation of PPI.

Differential amygdala activation during emotional decision and recognition memory tasks using unpleasant words: an fMRI study

This study used fMRI to examine the response of the amygdala in the evaluation and short-term recognition memory of unpleasant vs. neutral words in nine right-handed healthy adult women. To establish specificity of the amygdala response, we examined the fMRI BOLD signal in one control region (visual cortex). Alternating blocks of unpleasant and neutral trials were presented. During the emotional decision task, subjects viewed sets of three unpleasant or three neutral words while selecting the most unpleasant or neutral word, respectively. During the memory task, subjects identified words that were presented during the emotional decision task (0.50 probability). Images were detrended, filtered, and coregistered to standard brain coordinates. The Talairach coordinates for the center of the amygdala were chosen before analysis. The BOLD signal at this location in the right hemisphere revealed a greater amplitude signal for the unpleasant relative to the neutral words during the emotional decision but not the memory task, confirmed by Time Course x Word Condition ANOVAs. These results are consistent with the memory modulatory view of amygdala function, which suggests that the amygdala facilitates long-term, but not short-term, memory consolidation of emotionally significant material. The control area showed only an effect for Time Course for both the emotional decision and memory tasks, indicating the specificity of the amygdala response to the evaluation of unpleasant words. Moreover, the right-sided amygdala activation during the unpleasant word condition was strongly correlated with the BOLD response in the occipital cortex. These findings corroborate those by other researchers that the amygdala can modulate early processing of visual information in the occipital cortex. Finally, an increase in subject's state anxiety (evaluated by questionnaire) while in the scanner correlated with amygdala activation under some conditions.

Stability of reconstructed paralyzed shoulders using a reflected long head biceps technique

A new tendon transfer technique is proposed for the reconstruction of the paralyzed shoulders secondary to Brachial Plexus Injury (BPI). In this tendon transfer, the long head of the biceps tendons is utilized as a bridging tendon graft. It is reflected at the exit of the bicipital groove, passed through the deltoid and directed to the trapezius. The technique is referred to here as the Reflected Long Head Bicepts (RLHB) technique. This study evaluated the effect of this tendon transfer on the anterior, posterior, and inferior stability of the reconstructed should using cadaveric specimens. It was shown that loading of the RLHB contributed significantly to anterior stability of the reconstructed shoulder for 90 deg elevation in the scapula plane. The mean displacement was reduced by 56 percent with RLHB loaded (p<0.01), by 56 percent with the rotator cuff loaded (p <0.005), and by 67 percent with both the RLHB and the rotator cuff loaded (p<0.004). For the post-operation conditions, variation of the directions of RLHB had no significant effect on joint displacement in response to anterior loading. The RLHB tendon also contributed to the posterior and inferior stability for the low and middle elevations in the plane of scapula. Two variations of the RLHB tendon transfer procedures, namely the "Sub-Deltoid" and the "Through-Deltoid" techniques, were introduced and studied. These two techniques did not seem to have significantly different effects on the displacement of the humeral head in response to both posterior and inferior loading. The results of this study seemed to support the clinical feasibility of this tendon transfer approach as far as the biomedical stability of the reconstruction is concerned.

Regional and global changes in cerebral diffusion with normal aging

BACKGROUND AND PURPOSE

We used quantitative diffusion MR imaging to investigate the microstructural changes that occur in white matter during normal aging in order to identify regional changes in anisotropy and to quantify global microstructural changes by use of whole-brain diffusion histograms.

METHODS

Full diffusion tensor MR imaging was performed in 20 healthy volunteers, 20 to 91 years old. Thirteen subjects also underwent high-resolution T1-weighted imaging, so that diffusion images could be coregistered and standardized to normal coordinates for statistical probability mapping. Relative anisotropy (RA) was calculated, as was linear regression of RA with age for each pixel; pixels with a significant correlation coefficient were displayed. For histographic analysis, the average apparent diffusion coefficient (ADC) histograms were calculated on a pixel-by-pixel basis. Subjects were divided into two equal groups by the median age (55 years) of the population and plotted for statistical comparison.

RESULTS

Regional analysis showed statistically significant decreases in RA with increasing age in the periventricular white matter, frontal white matter, and genu and splenium of the corpus callosum, despite the absence of signal abnormalities on visual inspection of conventional images. Significant increases in RA were found in the internal capsules bilaterally. ADC histograms showed higher mean ADC and reduced peak height and skew in the older age group on group comparisons.

CONCLUSION

Quantitative diffusion histograms correlate with normal aging and may provide a global assessment of normal age-related changes and serve as a standard for comparison with neurodegenerative diseases.

Removal of the lateral or medial third of patellar tendon alters the patellofemoral contact pressure and area: an in vitro experimental study in dogs

OBJECTIVES

To compare patellofemoral contact pressure and areas after immediate removal of the lateral, central, or medial third of patellar tendon.

DESIGN

In vitro experiment in 12 dogs.

BACKGROUND

Alteration of the vector sum of the quadriceps muscle contraction after removal of partial patellar tendon might result in changes of patellar tracking in the trochlea.

METHODS

Patellofemoral contact pressure and areas were recorded using Fuji pressure-sensitive film at 45 degrees, 60 degrees, and 90 degrees of knee flexion under an isometric quadriceps force of 100% body weight. The patellofemoral contact imprint from the intact knees were obtained as control, and the lateral (n=4), central (n=4), and medial (n=4) third of the patellar tendon were subsequently removed and the patellofemoral contact imprint was recorded.

RESULTS

The patellofemoral contact area was found to increase with increasing knee flexion angles. No change in patellofemoral contact pressure and areas was found after removal of the central third patellar tendon. However, after removal of either lateral or medial third of patellar tendon, the patellofemoral contact was rotated with increasing knee flexion angles. This was due to the altered vector sum of the quadriceps force, resulting in significantly decreased patellofemoral contact areas and simultaneously a significantly increased contact pressure, characterized with concentration of patellofemoral contact pressure on both lateral and medial facets of the patellofemoral joint.

CONCLUSIONS

The results suggest that removal of the central third of patellar tendon may not alter the patellofemoral contact pressure and areas as compared with removal of either lateral or medial third of patellar tendon that may result in an altered postoperative tracking mechanism of the patellofemoral joint immediately after operation.

RELEVANCE

Findings of this in vitro animal study supports the use of central third of patellar tendon as autograft for anterior cruciate ligament reconstruction. However, further experimental studies are needed to investigate how the postoperative healing of the host patellar tendon will influence the findings obtained from this in vitro study.

Visual target detection paradigm for the study of selective attention

The current protocol can be used to examine selective attention. It has been used to acquire behavioral performance data in neurologically healthy normal control subjects and schizophrenic patients. A modified version, also described here, has been used to acquire functional neuroimaging data in normal subjects using positron emission tomography. Subject response accuracy and reaction times are recorded while subjects detect visual stimuli in either hemifield (left vs. right of a fixation point) or along the vertical meridian (above or below fixation). The lateralized presentation of stimuli permits the study of hemispheric specialization for selective attentional processes. Attentional load is manipulated by presenting larger-sized target stimuli alone (i.e., the letter 'O') or smaller-sized target stimuli surrounded by flanking letters. This protocol report includes a description of subject exclusion criteria, procedural details, relevant experimental conditions and variables, suggestions for data analysis, expected results, and a discussion of the protocol's significance for attentional research along with suggestions for future research.

Alteration of patellofemoral contact during healing of canine patellar tendon after removal of its central third

Alterations of the patellofemoral (PF) contact pressure and area were assessed using pressure-sensitive film after the removal of the central third of patellar tendon (PT) with healing over time in twelve dogs. The contralateral knee served as control. Histological sections were prepared for descriptive evaluation. No alterations in PT strain, PF contact pressure and area were measured immediately after the removal of the central third of PT compared with that before its removal. Compared with contralateral control, the healing of the donor PF induced a significantly increased PF contact area but not PF contact pressure in the specimens harvested at 6, 12, and 18 months after operation. Increased PF contact area indicated a proximal shift of the PF joint contact during flexion, which was associated with an increased strain of the healing PT under loading. The healing PT became hypertrophic compared with control, but the differences in the cross-sectional area were reduced over time. Histologically, a poorly organized extracellular matrix was observed at 6 months, with a progressive improvement in collagen fiber alignment up to 18 months postoperatively. The results of this study suggest that the removal of the central third of PT does not immediately change PF contact pressure and areas. However, remodeling of the healing tendon may cause an elongated PT, resulting in an increase in PF contact area under a given quadriceps force by knee extension.

Quantitative diffusion measurements in focal multiple sclerosis lesions: correlations with appearance on TI-weighted MR images

OBJECTIVE

Relative hypointensity on T1-weighted MR imaging has been suggested as a putative disability marker. The purpose of our study was to determine if there are quantifiable diffusion differences among focal multiple sclerosis lesions that appear differently on conventional T1-weighted MR images. We hypothesized that markedly hypointense lesions on unenhanced T1-weighted images would have significantly increased diffusion compared with other lesions, and enhancing portions of lesions would have different diffusion compared with nonenhancing lesions.

SUBJECTS AND METHODS

Average apparent diffusion coefficient (ADC) was calculated for 107 lesions identified on T2-weighted images in 16 patients with multiple sclerosis and was compared with the ADC of normal white matter in 16 age- and sex-matched control subjects. Seventy-five nonenhancing lesions (29 isointense, 46 hypointense) and 32 enhancing lesions (6 isointense, 26 hypointense) were categorized on the basis of unenhanced T1-weighted MR imaging.

RESULTS

Hypointense and isointense nonenhancing lesions both showed significantly higher ADC than normal white matter (p < 0.0001). Hypointense nonenhancing lesions showed higher ADC values than isointense nonenhancing lesions (p < 0.0001). Diffusion in enhancing portions of enhancing lesions was decreased when compared with nonenhancing portions.

CONCLUSION

Quantitative diffusion data from MR imaging differ among multiple sclerosis lesions that appear different from each other on T1-weighted images. These quantitative diffusion differences imply microstructural differences, which may prove useful in documenting irreversible disease.

Ultrastructure of white spot syndrome virus development in primary lymphoid organ cell cultures

Primary cell cultures from the lymphoid organ of Penaeus monodon were used to investigate in vitro propagation and morphogenesis of white spot syndrome virus (WSSV). Double-strength Leibovitz's L15 supplemented with 20% fetal bovine serum, pH 7.5, with a final osmolarity of 530 +/- 5 mOsm kg-1 was identified as the most suitable culture medium. In this medium, the lymphoid cells remained viable for more than 1 wk. Migrating cells were inoculated with WSSV, and the consequent cytopathic effects documented by light and electron microscopy. WSSV appears capable of following 2 alternative assembly sequences, one similar to the morphogenesis of the Oryctes rhinocerus virus and another which is more typical of baculoviral assembly. Possible relationships between WSSV, Oryctes virus, and baculoviruses are discussed.

Whole-brain diffusion MR histograms differ between MS subtypes

OBJECTIVE

To determine whether quantitative whole-brain MR diffusion histograms in patients with MS differ from those of normal control subjects.

BACKGROUND

MRI detects macroscopic cerebral lesions in MS, but the white matter lesion burden on MRI correlates imperfectly to clinical disability. Previous reports have further suggested abnormalities in white matter of MS patients with no visible lesions on conventional MRI.

METHODS

A total of 25 subjects (13 with MS [9 relapsing-remitting, 4 secondary progressive] and 12 healthy control subjects) underwent diffusion-weighted echoplanar MRI encompassing the entire brain. The average apparent diffusion coefficient (ADCave, or diffusion trace) was calculated on a pixel-by-pixel basis after segmentation of intracranial space from calvarium and extracranial soft tissues. Whole-brain ADCave histograms were calculated and plotted for statistical comparison.

RESULTS

Mean whole-brain MR ADCave in MS patients was elevated and histograms were shifted to higher values compared with normal control subjects. Mean whole-brain ADCave of secondary progressive patients was shifted to higher values compared with relapsing-remitting patients. Whole-brain ADCave histograms of relapsing-remitting patients showed no significant difference from normal control subjects.

CONCLUSION

Whole-brain MR diffusion histograms may quantitate overall cerebral lesion load in patients with MS and may be able to discern differences between clinical subgroups.

Direct interaction of two homeoproteins, homothorax and extradenticle, is essential for EXD nuclear localization and function

The Drosophila Homothorax (HTH) and Extradenticle (EXD) are two homeoproteins required in a number of developmental processes. EXD can function as a cofactor to Hox proteins. Its nuclear localization is dependent on HTH. In this study we present evidence of in vivo physical interaction between HTH and EXD, mediated primarily through an evolutionarily conserved MH domain in HTH. This interaction is essential for the mutual stabilization of both proteins, for EXD nuclear localization, and for the cooperative DNA binding of the EXD-HTH heterodimer. Some in vivo functions require both EXD and HTH in the nucleus, suggesting that the EXD-HTH complex may function as a transcriptional regulator.

Clinical trials of pacing mode selection

Current recommendations in favor of dual-chamber over single-chamber ventricular pacing for patients with sinus node dysfunction or AV conduction disorders were made largely based on observational data and expert opinions. The first randomized pacing mode selection study was relatively small and suggested survival advantage with physiologic pacing only after an extended follow-up duration of 5.5 years. Preliminary results of the first large-scale multicenter randomized pacing mode selection trial revealed only modest reduction in atrial fibrillation without survival advantage after 3 years of physiologic pacing. Two other large-scale multicenter randomized trials comparing physiologic versus ventricular pacing are currently ongoing. They may provide further scientific evidence based on which more objective recommendations can be made with respect to pacing mode selection.