Modulation of responses to optic flow in area 7a by retinotopic and oculomotor cues in monkey

Perception of two- and three-dimensional optic flow critically depends upon extrastriate cortices that are part of the 'dorsal stream' for visual processing. Neurons in area 7a, a sub-region of the posterior parietal cortex, have a dual sensitivity to visual input and to eye position. The sensitivity and selectivity of area 7a neurons to three sensory cues - optic flow, retinotopic stimulus position and eye position - were studied. The visual response to optic flow was modulated by the retinotopic stimulus position and by the eye position in the orbit. The position dependence of the retinal and eye position modulation (i.e. gain field) were quantified by a quadratic regression model that allowed for linear or peaked receptive fields. A local maximum (or minimum) in both the retinotopic fields and the gain fields was observed, suggesting that these sensory qualities are not necessarily linearly represented in area 7a. Neurons were also found that simply encoded the eye position in the absence of optic flow. The spatial tuning for the eye position signals upon stationary stimuli and optic flow was not the same, suggesting multiple anatomical sources of the signals. These neurons can provide a substrate for spatial representation while primates move in the environment.      

Synthetic or natural surfactants

Surfactant replacement therapy is one of the most studied interventions in neonatal medicine, with many thousands of infants having been enrolled in randomized clinical trials. It is clear that surfactant therapy reduces neonatal mortality and the risk of pulmonary air leaks in babies with or at risk of developing respiratory distress syndrome. Yet some doubts linger over other aspects of this therapy, despite it having been an acceptable and proven therapy for the past 7–10 years. As regards timing of treatment, the earlier the better, with true prophylaxis being reserved for babies of less than 28 weeks' gestation. Natural surfactant preparations containing surfactant proteins B and C act more rapidly than their synthetic protein-free counterparts and probably also have a greater impact on reducing neonatal mortality and pulmonary air leaks. Fears raised about immunological effects, prion transmission and chemical contamination of natural surfactants have not been substantiated. Long-term follow-up studies do not show any differences in outcome between treated and non-treated infants, except that the incidence and severity of retinopathy of prematurity might be reduced by treatment with natural surfactant. Further research is needed and this will include more detailed follow-up studies, newer indications for surfactant therapy and the testing of newer preparations with synthetic peptides or protein analogues added.     

Orthotopic cardiac transplantation: evaluation with CT

As cardiac transplantation has become widely available, computed tomography (CT) of the chest has played a useful role in the examination of patients after heart transplantation. To determine anatomic features related to the procedure, the authors evaluated 59 scans in 46 patients who had undergone orthotopic cardiac transplantation. Aortic anastomosis (seen in 98% of scans) and altered spacing between the great vessels (83%) proved to be the most common and most reliable findings. Other features including atrial anastomosis, high main pulmonary artery segment, remnant superior vena cava, and cardiac reorientation were also seen. Accurate interpretation of adenopathy, mediastinal abscess, and pericardial effusion will be enhanced in these patients through a better understanding of the cardiovascular-pericardial complex, which is afforded by CT.     

Experiences of special gynaecological services for children and adolescents: a descriptive study

Gynaecological examination of girls during childhood is undertaken somewhat infrequently. These genital examinations should not be taboo or a frightening experience for the girl, for her parents or for the physician. Studies of children suspected of sexual abuse have paid attention to the wide variety of gynaecological conditions already present in childhood. In 1988 we founded a special gynaecological outpatient clinic for girls under 16 y of age at a university hospital to develop the special knowledge and skills needed in children's gynaecology. In this gynaecological clinic for children and adolescents we were able to gain and offer expert knowledge of the problems of this age group. In this special clinic for children, gynaecological examination by special techniques and sonography led to a diagnosis in 71% of the patients without any instrumentation. Children and adolescent girls in need of special gynaecological care should be recognized specifically. Particular attention should be paid to the gynaecological care of victims of child sexual abuse and mentally or physically handicapped girls. In good co-operation with the girl, a gynaecological examination can become a positive experience during the development of female identity.     

Identification of the recombination site within the steroid 21-hydroxylase gene (CYP21) of the HLA-B47,DR7 haplotype.

The HLA haplotype A3-Cw6-B47-C4A91-BQ0-DR7 is associated with congenital adrenal hyperplasia (CAH), since it only carries the dysfunctional steroid 21-hydroxylase A pseudogene as well as the 5' adjacent complement C4A gene. The recombination site leading to the deletion of the complement C4B and steroid 21-hydroxylase B genes in this haplotype was studied by determining the 21-hydroxylase genomic DNA sequence in comparison to the standard CYP21A- and CYP21B-specific sequences. A 200-bp region between exons 7 and 8 was identified as a possible recombination site. Thus the deleted area comprises the 3' end of the CYP21A pseudogene, the entire C4B gene and the 5' end of the CYP21B gene. The findings were confirmed by PCR amplification of a 1.8-kb fragment of the CYP21 gene. This PCR system is specific for CYP21A/B recombinant genes and may be used for screening among CAH patients carrying this type of deletion.     

人参皂甙Rb1和Rg1对小鼠中枢神经递质受体和脑内蛋白质合成的影响

应用放射配基结合法测定了人参皂甙Rb₁和Rg₁对α₁,α₂,β肾上腺素能受体、M胆碱能受体、5-羟色胺、多巴胺及GABA等七种受体的作用。结果均不能证明它们对这七种受体有亲和力。但给动物ip药物连续5天,Rb₁和Rg₁均能使中枢M胆碱受体密度显著增高。Rb₁及Rg₁还能显著增加脑内蛋白质的含量。上述实验结果对解释人参的中枢作用提供了重要证据。     

Magnetic resonance imaging following unilateral occlusion of the renal circulation in rabbits

Magnetic resonance studies at 0.12 T were performed following acute unilateral occlusion of the renal artery or vein in rabbits. Prior to occlusion, in vivo and in vitro relaxation times of the renal cortex and outer medulla were similar. After venous occlusion, T1 and T2 were prolonged on the occluded side, while the contralateral side remained unchanged. After arterial occlusion, the outer medulla of both the occluded and contralateral kidney exhibited prolonged relaxation times. There was a significant linear correlation between T1, T2, and the water content of the tissue. The authors conclude that quantitative in vivo relaxation times may eventually prove to be useful in diagnosis, although at present they are less reliable than those obtained in vitro.     

基于受体结构的药物分子设计系统:维甲类分子与其结合蛋白之间相互作用的研究

大分子解剖程序,配体分子契合适配和DOCK程序,以及计算化学的其它程序等,已集成为基于受体结构和分子间相互作用的进行分子设计的软件系统,定名为BIOS(Biomolecularinteractionsandorientationsimulator)。BIOS软件可在普通的微机上运行。使用BIOS分别剥离了细胞浆维甲结合蛋白(CRBP)和副睾维甲酸结合蛋白(E-RABP)两种蛋白的配体结合腔,剥离是围绕配体以同样的分子距离进行的。从而得到了芳香性残基分布相似的两个结合腔,其结合位点的几何排布却有相当差别。揭示出的结合腔已用于一系列的维甲类化合物的DOCK研究。E-RABP的结合腔可做为设计新维甲类分子的模板。