Magnetic resonance imaging in neonatal encephalopathy

Magnetic resonance imaging may provide invaluable information in the term born neonate with encephalopathy. However, both hardware and sequences may need adaptation from normal adult protocols. Sedation is often required to obtain good quality imaging, but anaesthesia is not necessary in this population. The perinatal history may predict the pattern of brain lesions, which, in turn, may be used to predict the neurodevelopmental outcome. Image interpretation is not easy and requires a full clinical history in addition to experience of both normal and abnormal neonatal brain appearances. Lesions evolve rapidly, and perinatally acquired leasions are at the most obvious 1-2 weeks from delivery. Early imaging in the first few days from presentation should always include diffusion-weighted sequences to identify early ischaemic change. Advanced techniques such as venography, angiography and perfusion-weighted imaging may be useful in certain situations, and serial imaging may help differentiate perinatal-acquired lesions from other pathologies.     

GABA transporters as drug targets for modulation of GABAergic activity

The identification and subsequent development of the GABA transport inhibitor tiagabine has confirmed the important role that GABA transporters play in the control of CNS excitability. Tiagabine was later demonstrated to be a selective inhibitor of the GABA transporter GAT1. Although selective for GAT1, tiagabine lacks cell type selectivity and is an equipotent inhibitor of neuronal and glial GAT1. To date, four GABA transporters have been cloned, i.e., GAT1-4. The finding that some of these display differential cellular and regional expression patterns suggests that drugs targeting GABA transporters other than GAT1 might offer some therapeutic advantage over GAT1 selective inhibitors. Furthermore, it is particularly interesting that several recently defined GABA transport inhibitors have been demonstrated to display a preferential selectivity for the astrocytic GAT1 transporter. That cellular heterogeneity of GAT1 plays a role in the control of CNS function is confirmed by the demonstration that inhibition of astrocytic GABA uptake is highly correlated to anticonvulsant activity. At the present time, a functional role for the other GABA transporters is less well defined. However, recent findings have suggested a role for the mouse GAT2 (homologous to the human betaine transporter) in the control of seizure activity. In these studies, the non-selective GAT1 and mouse GAT2 transport inhibitor EF1502 (N-[4,4-bis(3-methyl-2-thienyl)-3-butenyl]-3-hydroxy-4-(methylamino)-4,5,6,7-tetrahydrobenzo[d]isoxazol-3-ol) was found to exert a synergistic anticonvulsant action when tested in combination with the GAT1 selective inhibitors tiagabine and LU-32-176B (N-[4,4-bis(4-fluorophenyl)-butyl]-3-hydroxy-4-amino-4,5,6,7-tetrahydrobenzo[d]isoxazol-3-ol). Additional studies will be required to define a role for the other GABA transporters and to further identify the functional importance of their demonstrated cellular and regional heterogeneity. A summary of these and other issues are discussed in this brief review.     

青蒿素的组织化学定位及其含量相关性研究

目的 确定青蒿素储存部位并为高青蒿素含量黄花蒿植株筛选提供选择指标。方法 应用组织化学方法确定青蒿素的储存结构，应用统计学方法确定储存结构腺毛状分泌腺密度与青蒿素含量的相关性。结果 青蒿素储存于腺毛状分泌腺(BGT)和T-型网状分泌腺(NTFT)中，在叶中腺毛状分泌腺的密度与青蒿素含量正相关。结论 腺毛状分泌腺密度可作为高青蒿素含量黄花蒿育种筛选指标。     

Large Electrocaloric Responsivity and Energy Storage Response in the Lead-Free Ba(GexTi1−x)O3 Ceramics

Ferroelectric property that induces electrocaloric effect was investigated in Ba(Ge_xTi_1−x)O₃ ceramics, known as BTGx. X-ray diffraction analysis shows pure perovskite phases in tetragonal symmetry compatible with the P4mm (No. 99) space group. Dielectric permittivity exhibits first-order ferroelectric-paraelectric phase transition, confirmed by specific heat measurements, similar to that observed in BaTiO₃ (BTO) crystal. Curie temperature varies weakly as a function of Ge-content. Using the direct and indirect method, we confirmed that the adiabatic temperature change ΔT reached its higher value of 0.9 K under 8 kV/cm for the composition BTG6, corresponding to an electrocaloric responsivity ΔT/ΔE of 1.13 × 10⁻⁶ K.m/V. Such electrocaloric responsivity significantly exceeds those obtained so far in other barium titanate-based lead-free electrocaloric ceramic materials. Energy storage investigations show promising results: stored energy density of ~17 mJ/cm³ and an energy efficiency of ~88% in the composition BTG5. These results classify the studied materials as candidates for cooling devices and energy storage applications.     

Expression of aldose reductase, sorbitol dehydrogenase and Na+/myo-inositol and Na+/Cl–/betaine transporter mRNAs in individual cells of the kidney during changes in the diuretic state

 The effect of changes in medullary extracellular tonicity on mRNA expression for aldose reductase (AR), sorbitol dehydrogenase (SDH), Na⁺/Cl^–/betaine (BGT) and Na⁺/myo-inositol (SMIT) cotransporter in different kidney zones was studied using Northern blot analysis and non-radioactive in situ hybridization in four groups of rats: controls, acute diuresis (the loop diuretic furosemide was administered), chronic diuresis (5 days of diuresis), and antidiuresis [5 days of diuresis followed by 24 h deamino-Cys¹,d-Arg⁸ vasopressin (dDAVP)]. Acute administration of the loop diuretic furosemide significantly reduced AR, SMIT and BGT gene expression in the inner and outer medulla compared with controls. Administration of dDAVP to chronically diuretic rats raised the expression of these three mRNAs in the inner but not the outer medulla compared with the chronically diuretic rats. None of these alterations in medullary tonicity significantly changed SDH expression. The in situ hybridization studies showed AR, BGT and SMIT mRNAs to be expressed in both epithelial and non-epithelial cells of the outer and inner medulla. The various cell types (epithelial, endothelial and interstitial cells) differed in their expression pattern and intensity of AR, SDH, BGT and SMIT mRNA, but the inner medullary cells responded uniformly to a decrease in extracellular tonicity with a reduction, and to an increase with enhancement of their AR, BGT and SMIT expression. Received: 26 May 1998 / Accepted: 14 September 1998     

Neuropsychological performance in OCD: a study in medication-naïve patients

Background

Obsessive-compulsive disorder (OCD) is associated with impairments in multiple neuropsychological domains but the findings are rather inconsistent across studies. One potential reason for poor replication is the confounding influence of medications. There is limited research on neuropsychological performance in medication-naïve, never treated OCD patients.

Methods

In this study, we assessed 31 medication-naïve, never-treated, DSM-IV OCD patients free of comorbid major depression and 31 healthy controls individually matched for age, gender and years of education, with tests of attention, executive function, memory reasoning and visuo-spatial function.

Results

Medication-naïve OCD patients did not significantly differ from healthy controls on most neuropsychological tests. Patients performed somewhat poorly only on the highest goal hierarchy of the Tower of London (TOL) test (p = 0.001, effect size = 0.68).

Conclusions

It is intriguing to find that symptomatic, drug-naïve OCD patients did not significantly differ from healthy controls on most neuropsychological tests. Our finding of medium effect size on TOL highest goal hierarchy test suggests that brain regions outside the affective orbitofrontal loop may also be perhaps involved in OCD. This finding however needs replication because of modest effect size. Future studies should focus on studying medication-naïve, co-morbidity-free patients and relatives using symptom dimensions for consistent and robust findings.     

Magnetic resonance imaging in hypoxic-ischaemic encephalopathy

Magnetic resonance imaging of the brain is invaluable in assessing the neonate who presents with encephalopathy. Successful imaging requires adaptations to both the hardware and sequences used for adults. Knowledge of the perinatal and postnatal details are essential for the correct interpretation of the imaging findings. Perinatal lesions are at their most obvious on conventional imaging between 1 and 2 weeks from delivery. Very early imaging is useful to guide management in ventilated neonates but abnormalities may be subtle on conventional sequences. Diffusion-weighted imaging (DWI) is clinically useful for the early identification of ischaemic tissue in the neonatal brain, the pattern of which can predict outcome. DWI may underestimate the final extent of injury, particularly basal ganglia and thalamic lesions. Serial imaging with quantification of both tissue damage and structure size provides invaluable insights into the effects of perinatal injury on the developing brain.     

青蒿素的组织化学定位及其含量相关性研究

目的 确定青蒿素储存部位并为高青蒿素含量黄花蒿植株筛选提供选择指标。方法 应用组织化学方法确定青蒿素的储存结构，应用统计学方法确定储存结构腺毛状分泌腺密度与青蒿素含量的相关性。结果 青蒿素储存于腺毛状分泌腺(BGT)和T-型网状分泌腺(NTFT)中，在叶中腺毛状分泌腺的密度与青蒿素含量正相关。结论 腺毛状分泌腺密度可作为高青蒿素含量黄花蒿育种筛选指标。     

Predicting successful dental examinations for children with autism spectrum disorder in the context of a dental desensitization program

Background

The authors evaluated the effectiveness of a dental desensitization program for children with autism spectrum disorder (ASD) and determined characteristics associated with a successful dental examination.