Cationic gemini surfactants with cleavable spacer: chemical hydrolysis, biodegradation, and toxicity.

The paper describes synthesis and characterization of a new type of cationic gemini surfactant, which has dodecyl tails and a spacer that contains an ester bond. The nomenclature used to describe the structure is 12Q2OCO1Q12, with Q being a quaternary ammonium group and the numbers indicating the number of methylene or methyl groups. Due to the close proximity to the two quaternary ammonium groups, the ester bond is very stable on the acid side and very labile already at slightly alkaline conditions. The hydrolysis products are two single chain surfactants (i.e. 12Q2OH and 12Q1COOH) which are less surface active than the intact gemini surfactant. 12Q2OCO1Q12 was found to be readily biodegradable, i.e. it gave more than 60% biodegradation after 28 days. This is interesting because similar gemini surfactants but with ester bonds in the tails instead of the spacer, have previously been found not to be readily biodegradable. The gemini surfactant was found to be toxic to aquatic organisms (ErC50 value of 0.27 mg/l), although less toxic than the two hydrolysis products.

Hippocampus, amygdala and global brain changes 10 years after childhood traumatic brain injury.

Traumatic brain injury (TBI) in children results in damage to the developing brain, particularly in severely injured individuals. Little is known, however, of the long-term structural aspects of the brain following childhood TBI. This study investigated the integrity of the brain 10 years post-TBI using magnetic resonance imaging volumetrics in a sample of 49 participants with mild, moderate and severe TBI, evaluated against a normative sample of 20 individuals from a pediatric database with comparable age and gender distribution. Structural integrity was investigated in gray and white matter, and by manually segmenting two regions of interest (hippocampus, amygdala), potentially vulnerable to the effects of childhood TBI. The results indicate that more severe injuries caused a reduction in gray and white brain matter, while all TBI severity levels resulted in increased volumes of cerebrospinal fluid and smaller hippocampal volumes. In addition, enlarged amygdala volumes were detected in severely injured patients compared to their mild and moderate counterparts, suggesting that childhood TBI may disrupt the development of certain brain regions through diffuse pathological changes. The findings highlight the lasting impact of childhood TBI on the brain and the importance of monitoring brain structure in the long-term after early injury.

The perception of real and illusory motion in schizophrenia.

An illusion of rapid movement is normally perceived when an attentional cue (such as a peripheral flash) preceeds the onset of a line. The movement is perceived as receding away from the cue. This study investigated how this illusion was perceived by people with schizophrenia. Nineteen participants with schizophrenia and 26 healthy matched controls were presented with a series of real, illusory, no motion or combined real and illusory motion stimuli at various target speeds. Detection thresholds were measured to determine the reliability of motion perception. The participants with schizophrenia were not distinguished from the control group in the perception of real motion. However, the motion detection curves for the schizophrenia group revealed a reduction in the perceptual effect of illusory motion in comparison to controls. The findings revealed that people with schizophrenia may be less easily deceived by illusory motion in comparison to healthy participants.

The Dimensions of Expansion: report of the 2007 NZAO Symposium.

The biennial symposium of the Education, Research and Development Group (ERDG) of the New ZealandAssociation of Orthodontists (NZAO) was held in Queenstown on August 17 and 18, 2007. Following a well-tested format, the symposium considered the effects of expansion of the dental arches in the three planes of space and over time, a timely but difficult topic given the current fashion to avoid the extraction of teeth to correct dental crowding. The findings reported here represent the consensus reached by delegates attending the symposium.

Imaging for Crohn disease: use of 3-T MRI in a paediatric setting.

This study was carried out to review our experience with 3-T MRI in the assessment of Crohn disease in a paediatric population. Twenty-four patients with biopsy proven Crohn disease identified on the radiology information system underwent abdominal MRI, with or without pelvic MRI. Twenty-eight studies were carried out on a 3-T scanner at a tertiary paediatric hospital. Eight of 24 of these (30%) had a gastrointestinal barium study, 2 of 24 (8%) a CT and 9 of 24 (38%) an abdominal ultrasound. The different MRI sequences were rated for observation of the bowel wall and abnormalities (0-5). The findings were correlated to relevant findings on endoscopy, examination under anaesthesia (EUA) and where available surgery, barium studies, CT and ultrasound. In this study, the colon was involved in 5 of 28 (18%), small bowel in 7 of 28 (25%), terminal ileum in 5 of 28 (18%). All the perineal studies (9 of 9) showed abnormalities. Sinus tracts or fistulas were identified in 7 of 28 (25%) studies. The mean rating of the different MRI sequences in showing bowel wall and changes of Crohn disease was T2 TSE 3.6, T2 half fourier aquisition single shot turbo spin echo (HASTE) with a long TE 3.6, T2 HASTE with short TE 3.4, true fast imaging with steady state precession (FISP) 2.7, T1 4.1 and Post-contrast T1 4.3. The T2 HASTE sequences with thinner slices improved observation. Detection of superficial abnormalities was similar on the 3D VIBE images and on the post-contrast T1 spin-echo (SE) sequences. In five of nine (56%) of those that had ultrasound, both studies were abnormal, with incomplete correlation of the abnormalities. Computed tomography and MRI were abnormal in two of two (100%) patients with good correlation of the abnormalities in one; in the other there was a minimal discrepancy in the estimation of the length of involved bowel. In 7 of 11 (64%) the barium study was abnormal. Good correlation to MRI findings was found in five of seven (71%) of patients. In two of seven (29%) both studies were abnormal, with incomplete correlation of the abnormalities. Barium underestimated the length of involved segment in these patients with inflammatory ileal thickening and ulceration. Notably, in both studies compression was limited because of patient discomfort and the involved segments obscured by overlap. Abdominal and pelvic MRI at 3 T is a useful imaging technique for evaluation of Crohn disease in the children. The extent of bowel wall involvement and extra-intestinal complications, such as abscesses and fistulas can be accurately assessed non-invasively, without the use of ionizing radiation or sedation.

The effects of illusory line motion on incongruent saccades: implications for saccadic eye movements and visual attention.

A complex neural problem must be solved before a voluntary eye movement is triggered away from a stimulus (antisaccade). The location code activated by a stimulus must be internally translated into an appropriate signal to direct the eyes into the opposite visual field, while the reflexive tendency to look directly at the stimulus must be suppressed. No doubt these extra processes contribute to the ubiquitous slowing of antisaccades. However, there is no consensus on the cognitive mechanisms that contribute to the antisaccade programme. Visual attention is closely associated with the generation of saccadic eye movements and it has been shown that attention will track an illusion of line motion. A series of experiments combined this illusion with a saccadic eye movement that was congruent (i.e. directed towards), or incongruent with (i.e. direct away from), a peripheral target. Experiment 1 showed that congruent saccades had faster reaction times than incongruent saccades. In contrast, Experiments 2 and 3 demonstrated that, with illusory line motion, incongruent saccades now had faster reaction times than congruent saccades. These findings demonstrate that an illusory phenomenon can accelerate the processing of an incongruent relative to a congruent saccade.

Insights into the acute cerebral metabolic changes associated with childhood diabetes.

AIMS: Type 1 diabetes is a prevalent chronic disease in childhood with the commonest single cause of death being cerebral oedema in the context of diabetic ketoacidosis (DKA). The nature of the alterations in cerebral metabolism that may result in vulnerability to neuronal injury remains unknown. The aim of this study was to analyse the magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) brain data from eight children with diabetes following acute presentation with hyperglycaemia with or without ketoacidosis, to determine the nature and timing of any alterations in cerebral structure and metabolism. METHODS: This study used MRI and MRS to investigate regional cerebral abnormalities in a small series of diabetic patients with and without DKA. Changes were compared with the clinical and biochemical features of the patients studied. RESULTS: Our small series of patients all demonstrated abnormal signal changes in the frontal region on fluid attenuated inversion recovery (FLAIR) MR imaging, suggestive of oedema, and spectroscopic abnormalities of increased taurine, myoinositol and glucose levels. The MR abnormalities varied in severity but did not correlate with any clinical or biochemical parameters. CONCLUSIONS: These changes indicate that many diabetic children, particularly at presentation, may have alterations in cerebral metabolism with implications for the pathogenesis and treatment of the cerebral complications of DKA. In addition, our findings suggest that increased taurine may be one of the important differentiating factors in the response of the brain of diabetic children to DKA that may reflect an increase in their vulnerability to cerebral oedema compared with diabetic adults.

Language cortex activation in normal children.

OBJECTIVE: To describe a protocol for use in young children and adolescents for determining language representation. METHODS: We performed 130 fMRI studies in 48 children and 17 adults. Verb generation (VG) and orthographic lexical retrieval (OLR) were used. The localization and lateralization of activation was rated visually. Regional voxel counts measured asymmetry and extent of activation. RESULTS: Activation was predominantly left-lateralized (children 85%, adults 94%), and there was no difference in the localization of activation for either paradigm. Children's typical sites of activation included mesial (96%), inferior (94%) and middle frontal (92%) gyri, the inferior (85%) and superior (65%) temporal cortex, and the cerebellum (67%). Less frequently activated sites were insular (50%) and posterior parietal (48%) cortices. Quantitative asymmetry index scores and visual inspection of laterality were concordant. Greater quantitative asymmetry for VG than OLR occurred in children. Laterality was not related to age, sex, task proficiency, or handedness. Frontal region voxel counts lower in children than adults and left sided counts correlated with task proficiency. CONCLUSIONS: Language fMRI can be performed in young children using resources available to clinical centers. The similarity in frequency of left language lateralization between children and adults suggests that language representation establishes early in development. The reduced amount of frontal region of interest activation in task-specific regions in children may reflect different levels of ability. However, the left-right distribution of activation does not appear to depend on task performance or age. These normative data provide a basis for decisions about language laterality in pediatric patients.

Assessment of the impact of the removal of cerebrospinal fluid on cerebral tissue volumes by advanced volumetric 3D-MRI in posthaemorrhagic hydrocephalus in a premature infant.

Current clinical practice in the premature infant with posthaemorrhagic ventricular dilatation (PHVD) includes drainage of cerebrospinal fluid (CSF). This case study used advanced volumetric three dimensional magnetic resonance imaging to document the impact of CSF removal on the volume of regional brain tissues in a premature infant with PHVD. The removal of a large volume of CSF was associated with an identical reduction in CSF volume, but more dramatically with a significant increase in the regional volumes of cortical grey matter and myelinated white matter. The alterations in cerebral cortical grey matter and myelinated white matter volumes may provide insight into the established association of PHVD with deficits in cognitive and motor functions.

Clinical and neuroradiologic features of acute disseminated encephalomyelitis in children.

OBJECTIVE: To identify the clinical and neuroradiologic features of acute disseminated encephalomyelitis (ADEM) in childhood. METHODS: A retrospective review was conducted of the medical records and MRI of children who presented to the Royal Children's Hospital in Melbourne with ADEM between January 1993 and December 1998. RESULTS: Of the 31 patients included in this study, 22 (71%) experienced a prodromal illness. Two patients (6%) had received hepatitis B vaccine 3 to 6 weeks before developing their illness. Symptoms and signs typically evolved over several days. Ataxia was the most common presenting feature, occurring in 20 patients (65%). MRI findings were variable, but lesions were most commonly seen bilaterally and asymmetrically in the frontal and parietal lobes. The authors found a high incidence of the corpus callosal and periventricular changes more typically associated with MS, but they also found a high rate of deep gray matter involvement (61% of patients). The use of high-dose IV methylprednisolone was usually associated with rapid recovery. Eighty-one percent of patients recovered completely, with only mild sequelae recorded in the remaining children. CONCLUSION: In the absence of a biological marker, the distinction between ADEM and MS cannot be made with certainty at the time of first presentation, but the authors suggest that a viral prodrome, early-onset ataxia, high lesion load on MRI, involvement of the deep gray matter, and absence of oligoclonal bands are more indicative of ADEM.

A patient temperature audit within a theatre recovery unit.

Hypothermia in the postoperative recovery phase can be a source of potential danger for patients emerging from anaesthesia. In spite of the vast amount of literature dealing with principles of care in the recovery room, information regarding the incidence of hypothermia appear very limited. This article presents a patient temperature audit to assess whether patients were being discharged from a theatre recovery unit hypothermic. In addition, patient temperatures were recorded both pre- and postoperatively, as well as on discharge from recovery, to monitor the incidence of hypothermia throughout the theatre suite. The results show that patients were being discharged with core body temperatures ranging from 34.8 to 38 degrees C with no incidence of hypothermia recorded when the operating room temperature was above 23 degrees C. In general, the coldest theatres were orthopaedic, with this group of patients showing the most incidence of hypothermia. This article aims to demonstrate the use of clinical audit to investigate and evaluate current practice.

Clinical and imaging features of cortical malformations in childhood.

OBJECTIVE: To determine the types, relative frequencies, clinical features, and MRI characteristics of malformations of cortical development (MCD) occurring in a cohort of children referred to a tertiary pediatric center. METHODS: Original MR images were reviewed by two investigators, who were blinded to clinical details, to determine the elemental imaging features of each malformation and to label these malformations according to an existing system of classification. Clinical information was collected by a review of hospital records. RESULTS: A total of 109 children with MCD were identified. There were 58 boys and 51 girls, age 8 days to 18 years at initial imaging (mean age, 5 years). Seizures were present in 75%, developmental delay or intellectual disability in 68%, abnormal neurologic findings in 48%, and congenital anomalies apart from the CNS malformation in 18%. The main malformations identified were heterotopic gray matter (19%), cortical tubers (17%), focal cortical dysplasia (16%), polymicrogyria (16%), agyria/pachygyria (15%), schizencephaly/cleft (5%), transmantle dysplasia (5%), and hemimegalencephaly (4%). Eight patients had features of more than one malformation. Most lesions were multilobar (47%), with the frontal lobe being the most common lobe involved (78%). A total of 68% of patients had other cerebral malformations including ventricular dilatation or dysmorphism (46%) and abnormalities of the corpus callosum (29%). CONCLUSIONS: This study illustrates the spectrum of MCD in a pediatric cohort and highlights some of the differences between pediatric and adult patients. Patients with MCD presenting in childhood have a wider spectrum of malformations and more varied, often more severe, clinical manifestations. The lesions are frequently multifocal or generalized and many are associated with noncortical developmental brain anomalies.

Congenital muscular dystrophy, white-matter abnormalities, and neuronal migration disorders: the expanding concept.

The congenital muscular dystrophies are a heterogeneous, recessively inherited group of disorders that have been subclassified on the basis of clinical central nervous system involvement. We report two children with "pure" congenital muscular dystrophy, one merosin negative and one merosin positive with extensive white matter and occipital cortical neuromigration abnormalities on magnetic resonance imaging (MRI). The first patient (merosin-negative congenital muscular dystrophy) presented with hypotonia and weakness in the neonatal period and subsequently was found to have a leukoencephalopathy and occipital cortical dysplasia on magnetic resonance imaging. The second patient presented with developmental delay without definite weakness. Initial investigations revealed a leukoencephalopathy and cortical dysplasia, but the patient subsequently was shown to have merosin-positive congenital muscular dystrophy. These patients illustrate that white-matter changes are not specific for merosin-negative congenital muscular dystrophy alone and that extensive cortical abnormality can be found in both groups of patients. In addition, our second patient illustrates a nonmuscular mode of congenital muscular dystrophy presentation that should be considered in patients with a "nonprogressive leukodystrophy."

Stroke and fibromuscular dysplasia: confirmation by renal magnetic resonance angiography.

Childhood stroke is uncommon and may require extensive evaluation to elucidate an underlying cause. A 9-year-old boy had clinical and magnetic resonance imaging (MRI) features of an ischemic event in the left middle cerebral artery territory. Magnetic resonance angiography (MRA) revealed beading of the left middle cerebral artery, consistent with irregular blood flow secondary to turbulence or luminal narrowing. Conventional angiography of the cerebral vessels confirmed the findings of cerebral MRA and raised further the suspicion of fibromuscular dysplasia (FMD). MRA of the renal vessels was subsequently performed, revealing beading of the left renal artery and confirming the diagnosis of FMD. MRA, a rapid and less invasive technique associated with far less morbidity and mortality as compared with conventional angiography, may prove to be as sensitive as conventional angiography in detecting the changes of FMD. MRA of the renal arteries should be performed with initial cranial MRI and MRA in children who present with cerebral infarction of possible vascular origin. This may obviate the need to perform further investigations and may make early diagnosis possible at the first MRI scan and under a single general anesthetic.

Acquisition and long-term retention of a gross motor skill in Alzheimer's disease patients under constant and varied practice conditions.

This study examined the acquisition and long-term retention of a gross motor skill, namely, tossing, in 23 moderately to severely demented Alzheimer's disease (AD) patients and 22 health older adults. To identify optimal learning strategies, subjects received 10 weeks of training under either constant or variable practice conditions. Accuracy at the tossing task was assessed immediately, one week, and one month following training. AD patients given constant practice were able to learn and retain the tossing task as well as healthy adults. Although controls performed equally well in both conditions, AD patients showed significantly less improvement when practiced at various distances from the target. By the one-month post-test, these patients had lost any minimal gains achieved through practice. In comparison, AD patients receiving constant practice showed essentially no forgetting across post-tests. The inability to benefit from varied practice suggests that AD patients may have difficulty accessing and/or forming motor schemas.

Vision in dementia: contrast effects.

Contrast sensitivity has been shown to be affected in Alzheimer's disease (Ad). We investigated low contrast acuity and contrast sensitivity using clinical test charts in this patient population. Additionally, we tested patients with vascular dementia (vd) and mixed dementia (md), (Alzheimer' with vascular dementia). Contrast sensitivity was assessed using the Vistech VCTS 6500 test chart. Low contrast acuity was measured using the Regan charts at four contrast levels (96%, 50%, 25% and 11%). The patient population consisted of 19 Ad patients, 9 vd patients and 10 md patients. Reduction in acuity was found with contrast level in all cases. Regression lines were fit to the data and statistical analysis was performed. We did not find a statistically significant difference between the Ad and vd or md groups. We did, however, find a difference between the vd and md groups. We did find reduction in contrast sensitivity at all spatial frequencies when compared to the elderly normal. Correspondingly, we found a significant difference in acuity when compared with normal data at the four contrast levels tested. Acuity is reduced with contrast in all patient groups. Our contrast sensitivity results are similar to those reported in the literature. This study points out the importance of using simple clinical test charts and further underscores the idea that there is a primary visual deficit in Ad.

Magnetic resonance angiography findings in the early post-carotid endarterectomy period.

This preliminary study was designed to investigate the ability of multiple axial volume three-dimensional fourier transform (3DFT) time-of-flight (TOF) magnetic resonance angiography (MRA) to depict the carotid bifurcation in the early post-carotid endarterectomy period. Five patients underwent intra-operative digital subtraction angiography (DSA) and carotid MRA within 5 days of carotid endarterectomy. An axial volume fast imaging in steady-state precession (FISP) gradient-echo 3DFT TOF carotid MRA technique in this limited series appeared to display accurately the surgically significant abnormalities at the carotid bifurcation after endarterectomy. However, in normal or near-normal intra-operative DSA studies, overestimation of internal carotid artery stenoses was encountered. Postoperative MRA demonstrates potential as a useful non-invasive investigation after carotid endarterectomy but should be interpreted with caution until larger studies become available.

The elusive character of agrammatism.

Traditionally, agrammatism was viewed as a restricted disorder of speech production which was associated with Broca's aphasia. This view has been replaced by a more complex picture which involves a range of linguistic impairments in both language production and comprehension. These disorders have been variously characterized as deficits, in the representation of linguistic structures and deficits in the on-line computation of sentence structures and their interpretations. A variety of analyses of production and comprehension in agrammatism, invoking both representational and computational analyses, are reviewed. Each has inadequacies, but, at the same time, it is argued that each also advances the understanding of agrammatism.