Yield of combined perfusion and diffusion MR imaging in hemispheric TIA

OBJECTIVE

Transient ischemic attacks (TIA) predict future stroke. However, there are no sensitive and specific diagnostic criteria for TIA and interobserver agreement regarding the diagnosis is poor. Diffusion-weighted MRI (DWI) demonstrates acute ischemic lesions in approximately 30% of TIA patients; the yield of perfusion-weighted MRI (PWI) is unclear.

METHODS

We prospectively performed both DWI and PWI within 48 hours of symptom onset in consecutive patients admitted with suspected hemispheric TIAs of <24 hours symptom duration. Two independent raters, blinded to clinical features, assessed the presence and location of acute DWI and PWI lesions. Lesions were correlated with suspected clinical localization and baseline characteristics. Clinical features predictive of a PWI lesion were assessed.

RESULTS

Forty-three patients met the inclusion criteria. Thirty-three percent had a PWI lesion and 35% had a DWI lesion. Seven patients (16%) had both PWI and DWI lesions and 7 (16%) had only PWI lesions. The combined yield for identification of either a PWI or a DWI was 51%. DWI lesions occurred in the clinically suspected hemisphere in 93% of patients; PWI lesions in 86%. PWI lesions occurred more frequently when the MRI was performed within 12 hours of symptom resolution, in patients with symptoms of speech impairment, and among individuals younger than 60 years.

CONCLUSIONS

The combination of early diffusion-weighted MRI and perfusion-weighted MRI can document the presence of a cerebral ischemic lesion in approximately half of all patients who present with a suspected hemispheric transient ischemic attack (TIA). MRI has the potential to improve the accuracy of TIA diagnosis. ACA = anterior cerebral artery; CI = confidence interval; DWI = diffusion-weighted MRI; ICA = internal carotid artery; MCA = middle cerebral artery; MRA = magnetic resonance angiography; MTT = mean transit time; OR = odds ratios; PCA = posterior cerebral artery; PWI = perfusion-weighted MRI; RR = risk ratios; TIA = transient ischemic attacks; TOAST = Trial of Org 10172 in Acute Stroke Treatment.

[From gene to disease; X-linked adrenoleukodystrophy]

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder, characterized by impaired peroxisomal beta-oxidation, subsequent accumulation of very long-chain fatty acids (> 22 carbon atoms), and mutations in the ABCD1 gene. Clinical manifestations, diagnostic procedures and treatment options are discussed.

Cholesterol-deprivation increases mono-unsaturated very long-chain fatty acids in skin fibroblasts from patients with X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is the most common peroxisomal disorder and is characterized by a striking and unpredictable variation in phenotypic expression. It ranges from a rapidly progressive and fatal cerebral demyelinating disease in childhood (CCALD), to the milder slowly progressive form in adulthood (AMN). X-ALD is caused by mutations in the ABCD1 gene that encodes a peroxisomal membrane located ABC half-transporter named ALDP. Mutations in ALDP result in reduced beta-oxidation of very long-chain fatty acids (VLCFA, >22 carbon atoms) in peroxisomes and elevated levels of VLCFA in plasma and tissues. Previously, it has been shown that culturing skin fibroblasts from X-ALD patients in lipoprotein-deficient medium results in reduced VLCFA levels and increased expression of the functionally redundant ALD-related protein (ALDRP). The aim of this study was to further resolve the interaction between cholesterol and VLCFA metabolism in X-ALD. Our data show that the reduction in 26:0 in X-ALD fibroblasts grown in lipoprotein-deficient culture medium (free of cholesterol) is offset by a significant increase in both the level and synthesis of 26:1. We also demonstrate that cholesterol-deprivation results in increased expression of stearoyl-CoA-desaturase (SCD) and increased desaturation of 18:0 to 18:1. Finally, there was no increase in [1-(14)C]-26:0 beta-oxidation. Taken together, we conclude that cholesterol-deprivation reduces saturated VLCFA, but increases mono-unsaturated VLCFA. These data may have implications for treatment of X-ALD patients with lovastatin.

Gene expression profiling in a mouse model for African trypanosomiasis

This study aimed to provide the foundation for an integrative approach to the identification of the mechanisms underlying the response to infection with Trypanosoma congolense, and to identify pathways that have previously been overlooked. We undertook a large-scale gene expression analysis study comparing susceptible A/J and more tolerant C57BL/6 mice. In an initial time course experiment, we monitored the development of parasitaemia and anaemia in every individual. Based on the kinetics of disease progression, we extracted total RNA from liver at days 0, 4, 7, 10 and 17 post infection and performed a microarray analysis. We identified 64 genes that were differentially expressed in the two strains in non-infected animals, of which nine genes remained largely unaffected by the disease. Gene expression profiling at stages of low, peak, clearance and recurrence of parasitaemia suggest that susceptibility is associated with high expression of genes coding for chemokines (e.g. Ccl24, Ccl27 and Cxcl13), complement components (C1q and C3) and interferon receptor alpha (Ifnar1). Additionally, susceptible A/J mice expressed higher levels of some potassium channel genes. In contrast, messenger RNA levels of a few immune response, metabolism and protease genes (e.g. Prss7 and Mmp13) were higher in the tolerant C57BL/6 strain as compared to A/J.

Methionine metabolism and phenotypic variability in X-linked adrenoleukodystrophy

A combined genotype of polymorphisms of methionine metabolism has been associated with CNS demyelination in methotrexate-treated patients. Within a sample of 86 patients with X-linked adrenoleukodystrophy, this genotype was overrepresented in a subgroup of 15 patients with adrenomyeloneuropathy (AMN) with CNS demyelination (adrenoleukomyeloneuropathy) in comparison to 49 AMN patients without CNS demyelination ("pure" AMN; p = 0.002), suggesting that methionine metabolism might contribute to the phenotypic variability in adrenoleukodystrophy.

Disputes over memory ownership: What memories are disputed?

The ownership of memories is sometimes disputed, particularly by twins. Examination of 77 disputed memories, 71 provided by twins, showed that most of the remembered events are negative and that the disputants appear to be self-serving. They claim for themselves memories for achievements and suffered misfortunes but are more likely to give away memories of personal wrongdoing. The research suggests that some of the memories in which we play a leading role might in fact have been the experiences of others.

Clinical importance of microbleeds in patients receiving IV thrombolysis

BACKGROUND

Cerebral microbleeds (MBs) detected on gradient echo (GRE) imaging may be a risk factor for hemorrhagic complications in patients with stroke treated with IV tissue plasminogen activator (tPA).

METHODS

The authors prospectively evaluated patients with acute ischemic stroke treated with IV tPA between 3 and 6 hours of symptom onset. MRI scans, including GRE imaging, were performed prior to tPA treatment, 3 to 6 hours after treatment and at day 30. The authors compared the frequency of hemorrhagic complications after thrombolysis in patients with and without MBs on their baseline GRE imaging.

RESULTS

Seventy consecutive patients (mean age, 71 +/- 29 years; 31 men, 39 women) were included. MBs were identified in 11 patients (15.7%) on baseline GRE imaging. There was no significant difference in the frequency of either symptomatic or asymptomatic hemorrhagic complications after thrombolysis between patients with and without MBs at baseline. None of the 11 patients with MBs (0%) at baseline had a symptomatic intracerebral hemorrhage compared with 7 of 59 patients who did not have baseline MBs (11.9%). In addition, no patients with baseline MBs had asymptomatic hemorrhagic transformation observed at the site of any pre-treatment MB.

CONCLUSIONS

The presence of cerebral microbleeds on gradient echo imaging does not appear to substantially increase the risk of either symptomatic or asymptomatic brain hemorrhage following IV tissue plasminogen activator administered between 3 and 6 hours after stroke onset.

Hepatitis C virus NS3-4A serine protease inhibitors: SAR of moiety with improved potency

We have discovered that introduction of appropriate amino acid derivatives at P'2 position improved the binding potency of P3-capped alpha-ketoamide inhibitors of HCV NS3 serine protease. X-ray crystal structure of one of the inhibitors (43) bound to the protease revealed the importance of the P'2 moiety.

Mapping of quantitative trait loci controlling trypanotolerance in a cross of tolerant West African N'Dama and susceptible East African Boran cattle

Trypanosomosis, or sleeping sickness, is a major disease constraint on livestock productivity in sub-Saharan Africa. To identify quantitative trait loci (QTL) controlling resistance to trypanosomosis in cattle, an experimental cross was made between trypanotolerant African N'Dama (Bos taurus) and trypanosusceptible improved Kenya Boran (Bos indicus) cattle. Sixteen phenotypic traits were defined describing anemia, body weight, and parasitemia. One hundred seventy-seven F2 animals and their parents and grandparents were genotyped at 477 molecular marker loci covering all 29 cattle autosomes. Total genome coverage was 82%. Putative QTL were mapped to 18 autosomes at a genomewise false discovery rate of <0.20. The results are consistent with a single QTL on 17 chromosomes and two QTL on BTA16. Individual QTL effects ranged from approximately 6% to 20% of the phenotypic variance of the trait. Excluding chromosomes with ambiguous or nontrypanotolerance effects, the allele for resistance to trypanosomosis originated from the N'Dama parent at nine QTL and from the Kenya Boran at five QTL, and at four QTL there is evidence of an overdominant mode of inheritance. These results suggest that selection for trypanotolerance within an F2 cross between N'Dama and Boran cattle could produce a synthetic breed with higher trypanotolerance levels than currently exist in the parental breeds.

ABCD1 mutations and the X-linked adrenoleukodystrophy mutation database: role in diagnosis and clinical correlations

X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene, which encodes a peroxisomal ABC half-transporter (ALDP) involved in the import of very long-chain fatty acids (VLCFA) into the peroxisome. The disease is characterized by a striking and unpredictable variation in phenotypic expression. Phenotypes include the rapidly progressive childhood cerebral form (CCALD), the milder adult form, adrenomyeloneuropathy (AMN), and variants without neurologic involvement. There is no apparent correlation between genotype and phenotype. In males, unambiguous diagnosis can be achieved by demonstration of elevated levels of VLCFA in plasma. In 15 to 20% of obligate heterozygotes, however, test results are false-negative. Therefore, mutation analysis is the only reliable method for the identification of heterozygotes. Since most X-ALD kindreds have a unique mutation, a great number of mutations have been identified in the ABCD1 gene in the last seven years. In order to catalog and facilitate the analysis of these mutations, we have established a mutation database for X-ALD ( http://www.x-ald.nl). In this review we report a detailed analysis of all 406 X-ALD mutations currently included in the database. Also, we present 47 novel mutations. In addition, we review the various X-ALD phenotypes, the different diagnostic tools, and the need for extended family screening for the identification of new patients.

Twins dispute memory ownership: a new false memory phenomenon

In three experiments, we examined a new memory phenomenon: disputed memories, in which people dispute ownership of a memory. For example, in one disputed memory each of two twins recollected being sent home from school for wearing too short a skirt, although only one of them was actually sent home. In Experiment 1, 20 sets of same-sex adult twins were asked to produce a memory for each of 45 words, and most twins spontaneously produced at least one disputed memory. In Experiment 2,20 different sets of same-sex adult twins rated disputed memories as higher in recollective experience, imagery, and emotional reliving than nondisputed memories. In Experiment 3, siblings who were close in age as well as same-sex friends were also found to have disputed memories, but less often than twins.

Experts discuss findings on drug resistance

John Mellors, MD, professor of medicine and chief of infectious diseases at the University of Pittsburgh, and Sharon Kemp, director of HIV Research for Virco UK in Cambridge, United Kingdom, answer questions about a study presented at the 5th International Workshop on HIV Resistance and Treatment Strategies, held in June in Scottsdale, AZ. The study found that a change at position 318 in the genetic code of HIV can make the virus highly resistant to treatment with non-nucleoside reverse transcription.

My story. Surviving a neurological accident

The piece that follows is a truly remarkable story of a young lady who experienced a devastating riding accident and lived to tell the tale. She has some interesting insights for us regarding the nursing of unconscious patients and the surprising recoveries that are sometimes possible for victims of brain damage. Sarah's story dramatically illustrates the importance of speaking positively in the presence of an unconscious patient.

Restoring pleasure: nutritional management of dysphagia

Dysphagia is associated with many different conditions and although widespread it is frequently not recognized. People with dysphagia are at risk of developing serious complications such at malnutrition, dehydration and aspiration. Texture modification, food fortification and dietary supplements are important elements in effective nutritional management of dysphagia and can also help bring back some of the pleasure to mealtimes. The ideal approach to the management of dysphagia involves a multidisciplinary team.

Delayed union stress fractures of the anterior tibia: conservative management

INTRODUCTION

A conservative method of treating four delayed union stress fractures of the anterior mid-tibia is described, with an illustrative case history.

METHODS

Once diagnosed each of the patients was treated in a pneumatic lower leg brace with modified rest. The mean (range) age of the patients was 28 (24-32) years and all were involved in professional or amateur sports. The mean (range) duration of symptoms before diagnosis and definitive treatment of the four fractures was 9 (3-14) months.

RESULTS

Use of this technique avoided the need for surgery in this group of patients and allowed return to unrestricted activity an average of 12 months from presentation.

CONCLUSION

The treatment is cost effective and avoids the often uncertain results and morbidity associated with surgery for these difficult stress fractures.

What happens if you retest autobiographical memory 10 years on?

Burt (1992a, 1992b) reported data on the autobiographical memory of diarists for events that had occurred on average 3.3 years earlier. This paper reports data on 11 of the diarists, who were recontacted after a further 10 years and who agreed to a retest of their memory. Estimates of event date and event duration from the two recall attempts were compared. As predicted, duration estimation was extremely stable and showed no detrimental effects of the additional 10 years of retention interval. Estimation of event date was predicted to show an increase in forward telescoping due to the increased remoteness of the event sample, but, contrary to this prediction, backward telescoping dominated dating errors. A combination of the establishment of a recent boundary and Kemp's (1999) associative model of dating is proposed as an explanation for these results. It is argued that the nature of dating errors may depend on the time of the event's occurrence in the life span and the age of the individual dating the events.

Solving the problem of weight control for tube-fed patients

Many patients requiring an enteral tube feed have low energy requirements or are overweight, with some patients gaining weight on as little as 1200 kcal/day. Most standard tube feeds supply 1500-2000 kcal/day. This has previously created a problem for dietitians and clinicians as giving a reduced volume to lower the energy supply has often resulted in the feed being incomplete with respect to vitamins, minerals and trace elements. A new feed, Fresubin1000 Complete, has been specially developed to overcome these difficulties. One litre supplies all nutrient requirements, including fibre, and only 1000 kcal. It is presented in a convenient, easy-to-use, pre-filled bag, the EasyBag. Fresubin1000 Complete is ACBS approved.