抑郁症患者的脑CT灌注成像特征与认知功能的相关性

摘要 目的：探讨抑郁症患者的脑CT灌注成像特征与认知功能的相关性。方法：选取我院2020年1月到2023年1月收治的90例抑郁症患者作为研究对象,将其分为观察组,另选取同期来我院体检的90名健康志愿者作为对照组。收集所有受检者脑CT灌注成像检查数据,分析抑郁症患者的脑CT灌注成像特征,并建立受试者工作特征（ROC）曲线分析脑CT灌注成像对抑郁症的诊断效能。随后对观察组和对照组受检者均进行认知功能评估,其中包括连线检测（TMT）、视觉再生测验（VRT）、言语流畅性测验（VF）、数字广度测验（DST）以及数字符号测验（SDMT）,并分析脑CT灌注成像与抑郁症认知功能的相关性。结果：观察组与对照组受检者rCBV、rCBF、MTT、TIP、右枕叶、左枕叶、右颞叶、左颞叶、右顶叶、左顶叶CT值对比无明显差异（P＞0.05）,观察组与对照组受检者右额叶、左额叶CT值对比差异显著,观察组明显低于对照组（P＜0.05）;90例抑郁症患者经过汉密尔顿抑郁量表（HAMD）评估后分数均＞20分,确定存在抑郁症状,脑CT灌注成像与HAMD评分诊断抑郁症的准确性、灵敏度、特异性、阳性预测值和阴性预测值对比无明显差异（P＞0.05）,脑CT灌注成像的曲线下面积为83.89,最佳诊断着色界限值为82.53%,HAMD评分的曲线下面积为84.26,最佳诊断着色界限值为87.57%;观察组与对照组受检者连线提笔数、连线错误数、视觉再生检测结果对比无明显差异（P＞0.05）,观察组与对照组受检者连线、言语流畅性、数字广度、数字符号检测结果对比差异显著（P＜0.05）;Spearman相关分析结果表明：连线提笔数、连线错误数、视觉再生与脑CT灌注参数均无明显相关性（P＞0.05）,连线、言语流畅性、数字广度、数字符号与rCBV、rCBF、MTT、TIP、右枕叶、左枕叶、右颞叶、左颞叶、右顶叶、左顶叶CT值无明显相关性（P＞0.05）,连线与右额叶、左额叶CT值呈负相关（P＜0.05）,言语流畅性、数字广度、数字符号与右额叶、左额叶CT值呈正相关（P＜0.05）。结论：抑郁症患者的脑CT灌注成像与健康群体呈现差异,其中右额叶、左额叶差异情况最为显著,提示抑郁症患者可能存在大脑额叶功能改变,另外,抑郁症患者的大脑额叶功能与认知功能变化具有明显相关性。     

Using Molecular Dynamics to Predict Factors Affecting Binding Strength and Magnetic Relaxivity of MRI Contrast Agents

We demonstrate the use of molecular dynamics and molecular mechanics methods to calculate properties and behavior of metal-chelate complexes that can be used as MRI contrast agents. Static and dynamic properties of several known agents were calculated and compared with experiment. We calculated the static properties such as the q-values (number of inner shell waters) and binding distances of chelate atoms to the metal ion for a set of chelates with known X-ray structure. The dynamic flexibility of the chelate arms was also calculated. These computations were extended to a series of exploratory chelate structures in order to estimate their potential as MRI contrast agents. We have also calculated for the first time the NMR relaxivity of an MRI contrast agent using a long (5 nsec) molecular dynamics simulation. Our predictions are promising enough that the method should prove useful for evaluating novel candidate compounds before they are synthesized. One novel static property, the projected area of chelate atoms onto a virtual surface centered on the metal ion (gnomonic projection), was found to give an effective measure of how well the chelate atoms use the free space around the metal ion.     

Are polyphosphates or phosphate esters prebiotic reagents?

It is widely held that there was a phosphate compound in prebiotic chemistry that played the role of adenosine triphosphate and that the first living organisms had ribose-phosphate in the backbone of their genetic material. However, there are no known efficient prebiotic synthesis of high-energy phosphates or phosphate esters. We review the occurrence of phosphates in Nature, the efficiency of the volcanic synthesis of P₄O₁₀, the efficiency of polyphosphate synthesis by heating phosphate minerals under geological conditions, and the use of high-energy organic compounds such as cyanamide or hydrogen cyanide. These are shown to be inefficient processes especially when the hydrolysis of the polyphosphates is taken into account. For example, if a whole atmosphere of methane or carbon monoxide were converted to cyanide which somehow synthesized polyphosphates quantitatively, the polyphosphate concentration in the ocean would still have been insignificant. We also attempted to find more efficient high-energy polymerizing agents by spark discharge syntheses, but without success. There may still be undiscovered robust prebiotic syntheses of polyphosphates, or mechanisms for concentrating them, but we conclude that phosphate esters may not have been constituents of the first genetic material. Phosphoanhydrides are also unlikely as prebiotic energy sources. Correspondence to: S.L. Miller     

Basic Fibroblast Growth Factor Selectively Increases AMPA-Receptor Subunit GluR1 Protein Level and Differentially Modulates Ca2+ Responses to AMPA and NMDA in Hippocampal Neurons

Abstract: The excitatory neurotransmitter glutamate is believed to play important roles in development, synaptic plasticity, and neurodegenerative conditions. Recent studies have shown that neurotrophic factors can modulate neuronal excitability and survival and neurite outgrowth responses to glutamate, but the mechanisms are unknown. The present study tested the hypothesis that neurotrophic factors modulate responses to glutamate by affecting the expression of specific glutamate-receptor proteins. Exposure of cultured embryonic rat hippocampal cells to basic fibroblast growth factor (bFGF) resulted in a concentration-dependent increase in levels of α-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)-receptor subunit GluR1 protein as determined by western blot, dot-blot, and immunocytochemical analyses. In contrast, bFGF did not alter levels of GluP2/3, GluR4, or the NMDA-receptor subunit NR1. Nerve growth factor did not affect GluR1 levels. Calcium-imaging studies revealed that elevation of [Ca²⁺]_i, resulting from selective AMPA-receptor activation, was enhanced in bFGF-pretreated neurons. On the other hand, [Ca²⁺]_i responses to NMDA-receptor activation were suppressed in bFGF-treated neurons, consistent with previous studies showing that bFGF can protect neurons against NMDA toxicity. Moreover, neurons pretreated with bFGF were relatively resistant to the toxicities of glutamate and AMPA, both of which were shown to be mediated by NMDA receptors. These data suggest that differential regulation of the expression of specific glutamate-receptor subunits may be an important mechanism whereby neurotrophic factors modulate activity-dependent neuronal plasticity and vulnerability to excitotoxicity.     

Quaternary structure of the hydroxylamine oxidoreductase from Nitrosomonas europaea

The hydroxylamine oxidoreductase from Nitrosomonas europaea was prepared to apparent electrophoretic homogeneity. Electron microscopy of negatively stained preparations of the sample revealed an overall diameter of about 8.8 nm of the enzyme particle. The native structure was determined as a tetrahedron-like assembly of identical subunits exhibiting four protein masses.Abbreviations ESI Electron spectroscopic imaging - HAO Hydroxylamine oxidoreductase     

Variable thermal sensitivity as output of a circadian clock controlling the bimodal rhythm of temperature choice in the ant Camponotus mus

Along a thermal gradient and under a LD 1212 h cycle, nurse workers of the ant Camponotus mus select for the brood two different temperatures daily: 30.8°C at the middle of the light period (circadian phase = 90°), and 27.5°C 8 h later, during the dark period (CP = 210°). Brood-carrying activity proved to be self-sustained, running its two daily bursts free with a similar period of 23.5 h, under both LL and DD. The LD alternation acted as a strong Zeitgeber. A phase-delay of the LD 1212 h cycle reset the overt rhythm at once, being both daily events locked-on to the delayed light: dark transition. However, changes in expression, non-occurrence, or even splitting of the two daily brood-carrying events during resetting depended on the phase of the delayed DL transition. By comparing the occurrence of activity with predictions based on a threshold curve of thermal sensitivity, results indicated that an immediate resetting of the involved pacemaker actually takes place. Nurse workers do not directly control the total time spent by the brood at the selected temperature. Instead, the endogenously-driven thermal sensitivity triggers their thermal-searching behavior at two critical times of the day, when environmental temperature is expected to reach its maximum and minimum.     

Food habits of channel catfish in a reservoir receiving heated waters

The diet of channel catfish captured near the mouth of a channel carrying heated waters was not significantly different from the diet of catfish captured elsewhere in the same reservoir during the cool months of the year. In summer months, however, the diet of catfish captured near the effluent was significantly different from the diet of catfish from other locations and seemed to indicate that catfish were foraging in cool, deeper waters beneath the thermal plume.Department of Biological Sciences, North Texas State UniversityFinancial support for the study was provided by a Faculty Research Grant at North Texas State University.     

High resolution microanalysis for phosphorus in Golgi complex beads of insect fat body tissue by electron spectroscopic imaging

Golgi complex beads are 10 nm particles arranged in rings on the smooth forming face of the Golgi complex that stain specifically with bismuth in arthropod cells. In vitro experiments with biological molecules spotted on to cellulose acetate strips indicated that bismuth bound to the beads through phosphate groups. We could detect a weak phosphorus signal from the beads using a new technique called electron spectroscopic imaging that is capable of very high spatial resolution (0.3–0.5 nm) and sensitivity (50 atoms of phosphorus). Detection was not obscured by tissue staining with bismuth or uranyl acetate or by using an inorganic buffer (Na cacodylate). Localization of phosphorus was greatly improved by using colour-enhanced computer pictures of the electron spectroscopic images and quantitating the images. The results indicate that the phosphorus content of the beads is large enough to account for their bismuth reactivity.