Assessment of spinal cord trauma using evoked potentials in a rat model of decompression sickness

A rapid quantitative technique for assessing spinal cord trauma in a rat model of decompression sickness is described. Evoked potentials are measured from the lower limbs of rats before and after dives with compressed air in a hyperbaric chamber. Under chloral hydrate anesthesia, the sciatic nerve is stimulated at the sciatic notch with needle electrodes and platinum/iridium electrodes are used to record the action potentials from the plantar muscles. Analysis showed that the sensory reflex response was markedly depressed in the rats soon after diving and did not recover for up to 5 days. The motor response was similarly affected although to a lesser degree. The latency of the reflex response also became prolonged after 3 days. The significant and complex pattern of neurological dysfunction shown by this electrophysiologic technique validates the use of the rat model for the study of spinal cord decompression sickness. This technique should aid studies aimed at testing new therapies for this disease.     

Analysis of heart rate variability signal during meditation using deterministic-chaotic quantifiers

Abstract

This study investigated the level of chaos and the existence of fractal patterns in the heart rate variability (HRV) signal prior to meditation and during meditation using two quantifiers adapted from non-linear dynamics and deterministic chaos theory: (1) component central tendency measures (CCTMs) and (2) Higuchi fractal dimension (HFD). CCTM quantifies degree of variability/chaos in the specified quadrant of the second-order difference plot for HRV time series, while HFD quantifies dimensional complexity of the HRV series. Both the quantifiers yielded excellent results in discriminating the different psychophysiological states. The study found (1) significantly higher first quadrant CCTM values and (2) significantly lower HFD values during meditation state compared to pre-meditation state. Both of these can be attributed to the respiratory-modulated oscillations shifting to the lower frequency region by parasympathetic tone during meditation. It is thought that these quantifiers are most promising in providing new insight into the evolution of complexity of underlying dynamics in different physiological states.     

含种子细胞的丝素组织工程神经移植物修复大鼠脊髓损伤

目的 探讨体外构建含种子细胞的蚕丝丝素组织工程神经移植物(TENGs)的方法,评价其对大鼠脊髓损伤修复的影响。方法 分离大鼠皮肤前体细胞并向施万细胞诱导分化,S-100免疫荧光染色鉴定。将皮肤前体细胞诱导分化的施万细胞（SKP-SCs）作为种子细胞,联合蚕丝丝素神经导管和纤维支架共培养。共培养7d后将蚕丝丝素TENGs置入大鼠背侧T8~T10半横断损伤的脊髓中,于术后不同时间点利用BBB评分观察行为学的变化,术后8周取材,切片,免疫荧光染色观察脊髓损伤修复情况以及种子细胞的存活情况。 结果 相差显微镜下体外培养的SKP-SCs大部分细胞形态呈双极或3极,免疫荧光染色显示,SKP-SCs呈S-100阳性,将SKP-SCs与蚕丝丝素支架材料共培养,蚕丝丝素支架表面均匀贴附大量的细胞,生长状态良好。将该移植物移植入大鼠T8~T10半横断损伤脊髓处,术后BBB评分显示,从4周起至8周均优于对照组,且结果具有统计学差异;术后8周时取材切片仍能观察到大鼠体内有大量种子细胞存活。 结论 含种子细胞的蚕丝丝素组织工程神经移植物对于修复大鼠脊髓损伤具有一定的促进作用。     

Detection of allelic imbalance in the gene expression of <Emphasis Type="Italic">hMSH2</Emphasis> or <Emphasis Type="Italic">RB1</Emphasis> in lymphocytes from pedigrees of hereditary,nonpolyposis, colorectal cancer and retinoblastoma by an RNA difference plot

A number of phenotypes in hereditary disorders or common diseases are associated with specific genotypes. However, little is known about the molecular basis of phenotypic variation among individuals carrying the same mutation or polymorphism. Here, a highly quantitative approach was taken to examine a relative amount of mRNA from two polymorphic alleles with a coefficient of variation of less than 10% using an RNA difference plot (RDP). RDP analysis revealed that most genes examined were expressed in equal amount from the two alleles in normal lymphocytes. In contrast, the relative amounts of hMSH2 or RB1 mRNAs carrying premature termination codons were significantly reduced compared with those of wild-type mRNAs in lymphocytes from carriers of hereditary, nonpolyposis, colorectal cancer and hereditary retinoblastoma. The balance of allelic expression of the RB1 was also significantly impaired in a pedigree of retinoblastoma carrying a missense mutation in codon 661. The relative expression of the mutant to the wild-type RB1 alleles among the carriers varied from 0.40 to 2.39. The analysis of the expression diversity of a disease-associated allele by RDP could provide a novel approach to elucidating the mechanisms underlying phenotypic variation among individuals carrying an identical mutation or polymorphism at a single locus.