鼻腔结构影响人体嗅觉反应的数值模拟

采用一个符合实际解剖学的鼻腔结构,建立了鼻腔仿生模型和气味分子传输过程的控制方程,应用ANSYS软件,对鼻腔流场进行了数值模拟。结果显示吸气速度越大,流过嗅觉区的气味分子越多,越容易产生嗅觉;鼻腔入口处到嗅觉区的距离越短,流过嗅觉区的气味流量越大,越容易产生嗅觉。从而,丰富了嗅觉理论,使人们进一步认识嗅觉,为人工嗅觉提供了仿生理论依据。     

Alleviation of Stress-Induced Damage to Rat Brain Cells by Transcranial Electromagnetic Stimulation

Biophysics - The effect of transcranial electromagnetic stimulation on immobilization stress-induced damage to rat brain cells was studied. Electromagnetic stimulation was performed by microwave...     

Noninvasive Transcranial Electrostimulation of the Brain Endophrinergic Structures: Effects on Human Fatigue and Related Psychophysiological Indices

A randomized single-blind passive placebo-controlled study using a set of seven subjective and objective psychophysiological tests that evaluated the background state and changes in 26 psychophysiological indices (including the physical, cognitive, and affective components of fatigue) showed that transcranial electrostimulation (TES) of endorphinergic structures of the human brain facilitates the normalization of most indices. The positive effects of TES were more pronounced in subjects with strong negative shifts of the initial indices, which suggests a homeostatic character of the effects of activation of the brain endorphin-mediated mechanisms. Special attention was paid to the use of an analog scale for rapid evaluation of fatigue whose validity, reliability, and applicability were proved experimentally by the method of correlation matrices.     

An Antibody Specific for Component 8 of Myelin Basic Protein from Normal Brain Reacts Strongly with Component 8 from Multiple Sclerosis Brain

Myelin basic protein (MBP) consists of several components or charge isomers (C-1 through C-8) generated by one or a combination of posttranslational modifications. One of these, C-8, has been shown to contain citrulline (Cit) at defined sites formed by deimination of six arginyl residues. This unusual modification has allowed us to raise antibodies specific for this charge isomer only. To do this, a synthetic peptide, Gly-Cit-Cit-Cit-Cit, was coupled to keyhole limpet hemocyanin and injected into rabbits. The antibodies so generated reacted only with C-8 and not with any of the other charge isomers. A second antibody fraction was raised against the synthetic peptide ACitHGFLPCitHR naturally occurring between residues 24 and 33 of C-8 (all other charge isomers contain R instead of Cit at positions 25 and 31). These antibodies preferred C-8 but reacted with the other charge isomers, to the extent of approximately 25-30% of the reactivity shown with C-8. In studies with C-8 from multiple sclerosis (MS) MBP, much greater reactivity was obtained with these antibodies when compared with their reactivity with C-8 from normal MBP. Because the total number of Cit residues in C-8 from MS and normal MBP is the same, the difference in reactivity may be related to structural factors. The antibodies raised with the tetra-Cit peptide were reacted with three pairs of synthetic peptides: 24ARHGFLPRHR33 and ACitHGFLPCitHR; 120GQRPGFGYGGRAS132 and GQCitPGFGYGGCitAS; and 157GGRDSRSGSPMARR170 and GGCitDSRSGSPMACitR. They reacted only with the Cit-containing peptides in the order 157-170 greater than 120-130 greater than 24-33.(ABSTRACT TRUNCATED AT 250 WORDS)     

Transcranial Red and Near Infrared Light Transmission in a Cadaveric Model

Background and Objective

Low level light therapy has garnered significant interest within the past decade. The exact molecular mechanisms of how red and near infrared light result in physiologic modulation are not fully understood. Heme moieties and copper within cells are red and near infrared light photoreceptors that induce the mitochondrial respiratory chain component cytochrome C oxidase, resulting in a cascade linked to cytoprotection and cellular metabolism. The copper centers in cytochrome C oxidase have a broad absorption range that peaks around 830 nm. Several in vitro and in vivo animal and human models exist that have demonstrated the benefits of red light and near infrared light for various conditions. Clinical applications for low level light therapy are varied. One study in particular demonstrated improved durable functional outcomes status post-stroke in patients treated with near infrared low level light therapy compared to sham treatment [1]. Despite previous data suggesting the beneficial effect in treating multiple conditions, including stroke, with low level light therapy, limited data exists that measures transmission in a human model.

Study Design/Materials and Methods

To investigate this idea, we measured the transmission of near infrared light energy, using red light for purposes of comparison, through intact cadaver soft tissue, skull bones, and brain using a commercially available LED device at 830 nm and 633 nm.

Results

Our results demonstrate that near infrared measurably penetrates soft tissue, bone and brain parenchyma in the formalin preserved cadaveric model, in comparison to negligible red light transmission in the same conditions.

Conclusion

These findings indicate that near infrared light can penetrate formalin fixed soft tissue, bone and brain and implicate that benefits observed in clinical studies are potentially related to direct action of near infrared light on neural tissue.     

低照度光疗法在脑损伤疾病治疗方面的研究进展

由于传统方法在脑疾病治疗方面的局限性,低照度光疗法越来越受到重视。低照度光疗法利用波长在600 nm-1 100 nm的低功率激光或者准单色光以非破坏和非热行为来调制生物过程,用于促进伤口愈合,抑制感染、水肿以及减轻疼痛等。近来,研究者进行了大量低照度光治疗脑损伤疾病方面的实验,研究对象从细胞、动物模型到人类,病症从卒中,急性脑创伤到慢性脑损伤以及神经退行性病变等。研究结果表明,低照度光疗法有可能应用于脑部损伤疾病的治疗。介绍了低照度光疗法的机理、应用,并对低照度光疗法的治疗参数,包括治疗窗口、波长以及剂量等进行了回顾。     

Parvalbumin in Human Brain

Parvalbumin was isolated from human cerebral cortex and biceps and triceps muscles by HPLC. The immunological properties of the human protein and the mobility in two-dimensional polyacrylamide gels were similar to that of parvalbumin isolated from the muscles of rat, mouse, rabbit, and chicken. The tryptic peptide maps of the human parvalbumin, however, differed considerably from all other parvalbumins, indicating a distinct primary structure. The immunolabeled cells in the hippocampus of the human brain were of different sizes and forms; they occurred in all subfields and probably represent interneurons.     

d-Aspartate in Human Brain

The presence of the biologically uncommon D-aspartic acid (D-aspartate) in human brain white matter has been previously reported. The earlier study has now been expanded to include D/L-aspartate ratios from 67 normal brains. The data show that the D-aspartate content increases rapidly from 1 year to approximately 35 years of age, levels off in middle age, and then appears to decrease somewhat. The D-aspartate content in gray matter remains at a consistently low level (half of that found in white matter) throughout the human life span. Within the limitations of current analytical methods, there was no detectable difference in D/L-aspartate ratios in white and gray matter of brains with Alzheimer's disease and several other pathologies when compared with brains of normal subjects. However, the presence of a significant D-aspartate level in white matter during the adult life span may lead to changes in protein configuration related to dysfunctions associated with the aging brain.     

Listening to the Human Voice Alters Sensorimotor Brain Rhythms

While neuronal desynchronization in the mu (^≈10Hz) and beta (^≈20Hz) frequency bands has long been known to be an EEG index of sensorimotor activity, this method has rarely been employed to study auditory perception. In the present study, we measured mu and beta event-related desynchronisation (ERD) while participants were asked to listen to vocal and triangle-wave melodies and to sing them back. Results showed that mu and beta ERD began earlier and were stronger when listening to vocal compared to non-vocal melodies. Interestingly, this humanness effect was stronger for less accurate singers. These results show that voice perception favors an early involvement of motor representations.     

Acid Sphingomyelinase of Human Brain: Purification to Homogeneity

Abstract: Acid sphingomyelinase (sphingomyelin phosphodiesterase, EC 3.1.4.12) was purified from human brain by extraction with 0.1% Triton X-100, followed by sequential chromatography on Concanavalin A-Sepharose, octyl-Sepharose, hydroxylapatite, DEAE-cellulose, red A-agarose, Sephadex G-200, and DEAE-cellulose with ampholyte elution. Sphingomyelinase activity was purified more than 20,000-fold from the starting homogenate with a 1% yield. Specific activity of up to 800 μmol/h/mg protein could be achieved. Gel electrophoresis with 6% polyacrylamide containing sodium dodecyl sulfate gave a single protein band with a molecular weight of 70,000, in good agreement with the molecular weight previously estimated from sucrose density gradient centrifugation in 0.1% Triton X-100. Triton X-100 could be readily removed from the enzyme by sucrose density gradient centrifugation. The Triton-free enzyme showed the same K _m and pH optimum. Heat stability of the enzyme was reversibly affected by Triton X-100, in that removal of the detergent made the enzyme more heat labile. The K _m of purified enzyme for sphingomyelin was 36 μ M . It was unaffected by sulfhydryl reagents, but was inhibited by dithiothreitol at high concentrations. The preparation was free of all lysosomal hydrolase activities tested, including galactosylceramidase and α-mannosidase, which tended to copurify in our previous procedure. The enzyme was inactive toward sphingosylphosphorylcholine. It was active with bis[ p -nitrophenyll- and bis[4-methylumbelliferyl]phosphate and the chromogenic and fluorogenic sphingomyelin analogues.     

Selectivity to Translational Egomotion in Human Brain Motion Areas

The optic flow generated when a person moves through the environment can be locally decomposed into several basic components, including radial, circular, translational and spiral motion. Since their analysis plays an important part in the visual perception and control of locomotion and posture it is likely that some brain regions in the primate dorsal visual pathway are specialized to distinguish among them. The aim of this study is to explore the sensitivity to different types of egomotion-compatible visual stimulations in the human motion-sensitive regions of the brain. Event-related fMRI experiments, 3D motion and wide-field stimulation, functional localizers and brain mapping methods were used to study the sensitivity of six distinct motion areas (V6, MT, MST+, V3A, CSv and an Intra-Parietal Sulcus motion [IPSmot] region) to different types of optic flow stimuli. Results show that only areas V6, MST+ and IPSmot are specialized in distinguishing among the various types of flow patterns, with a high response for the translational flow which was maximum in V6 and IPSmot and less marked in MST+. Given that during egomotion the translational optic flow conveys differential information about the near and far external objects, areas V6 and IPSmot likely process visual egomotion signals to extract information about the relative distance of objects with respect to the observer. Since area V6 is also involved in distinguishing object-motion from self-motion, it could provide information about location in space of moving and static objects during self-motion, particularly in a dynamically unstable environment.     

Extraocular Muscle Characteristics Related to Myasthenia Gravis Susceptibility

Background

The pathogenesis of extraocular muscle (EOM) weakness in myasthenia gravis might involve a mechanism specific to the EOM. The aim of this study was to investigate characteristics of the EOM related to its susceptibility to myasthenia gravis.

Methods

Female F344 rats and female Sprague-Dawley rats were assigned to experimental and control groups. The experimental group received injection with Ringer solution containing monoclonal antibody against the acetylcholine receptor (AChR), mAb35 (0.25 mg/kg), to induce experimental autoimmune myasthenia gravis, and the control group received injection with Ringer solution alone. Three muscles were analyzed: EOM, diaphragm, and tibialis anterior. Tissues were examined by light microscopy, fluorescence histochemistry, and transmission electron microscopy. Western blot analysis was used to assess marker expression and ELISA analysis was used to quantify creatine kinase levels. Microarray assay was conducted to detect differentially expressed genes.

Results

In the experimental group, the EOM showed a simpler neuromuscular junction (NMJ) structure compared to the other muscles; the NMJ had fewer synaptic folds, showed a lesser amount of AChR, and the endplate was wider compared to the other muscles. Results of microarray assay showed differential expression of 54 genes in the EOM between the experimental and control groups.

Conclusion

Various EOM characteristics appear to be related to the increased susceptibility of the EOM and the mechanism of EOM weakness in myasthenia gravis.     

Gangliosides in Human Fetal Brain

The ganglioside concentration and composition were determined in 42 human fetal brains from gestational week 10 to 22, a period that is morphologically characterized by rapid neuroblast proliferation and migration. The ganglioside concentration was constant during this period, approximately 1 mumol of ganglioside sialic acid/g of fresh tissue weight. At gestational week 10 the ganglioside pattern was dominated by gangliosides of the ganglio b series, with the major ganglioside being GT1b, contributing 40% of total ganglioside sialic acid, whereas GD1b and GD3 contributed only 15 and 10%, respectively. The proportion of b series ganglioside decreased to gestational week 22, with the most pronounced relative reduction affecting GD3, but also GT1b and GD1b to a lesser extent. The ganglioside GQ1b increased in content from gestational week 10 and peaked around week 16. The proportion of GD1a increased markedly between gestational week 12 and 14 and slowly between week 14 and 18 and then increased rapidly from week 20. Ganglioside GM1 underwent a similar change. Gangliosides of the lacto series contributed 6-10% of ganglioside sialic acid between gestational week 10 and 15, and thereafter the proportion slowly decreased. 3'-isoLM1 decreased rapidly in content from gestational week 10 (20 nmol/g of fresh weight) to week 22 (less than 0.5 nmol/g of fresh weight), whereas the gangliosides of the neolacto series (3'-LM1 and 3',8'-LD1) showed a slower and less marked decline in level. The biological significance of the ganglioside changes is discussed.     

Thermodynamics of the Human Brain

The human brain may be regarded as an irreversible system which is constrained by a fixed inflow of free energy in the form of chemical nourishment from within the body and information from the environment. The evolution of the internal spontaneous process may be described as a path on the saddle surface of entropy production rate in the configuration space of the process variables. From any initial state of high entropy production the system evolves towards the saddle point by a series of regessions to temporary minima alternating with fluctuations which introduce new internal constraints and open new channels for regression. The spontaneous regression steps of the process are to be associated with the learning process and the deductive processes of thought since information is necessarily being stored, whereas the fluctuation or nucleation steps are to be associated with the inductive or creative part of the thought process. The state of consciousness is to be associated with the system undergoing regression. If, under certain boundary conditions, the system attains the stable saddle point, a state of unconsciousness is attained in which no change of state variables occurs in time. The stability of this state is indicated by its resistance to perturbation.