CO2 dissociation curves of oxygenated whole blood obtained at rest and in exercise

Summary In vitro CO₂ dissociation curves for oxygenated whole blood were determined in 19 healthy male subjects at rest and during submaximal and maximal bicycle work. Hemoglobin concentration and blood lactate increased with increasing work load and accordingly buffer value of the whole blood increased while bicarbonate and Base Excess (BE) decreased, resulting in a downward shift of the CO₂ dissociation curve during exercise. Despite the marked increase in buffer values of the blood, the slopes of the CO₂ dissociation curves during exercise were found to be about the same as those obtained at rest. It was inferred that the increasing effect of increased buffer value, on the dissociation slope, was essentially compensated by the decreasing effect of diminished bicarbonate content. The advantages of this relatively constant CO₂ dissociation slope for the indirect measurement of cardiac output by the Fick principle are discussed.     

Morphological variability, lectin binding and Na+,K+-activated adenosine triphosphatase activity of isolated Müller (glial) cells from the rabbit retina

Rabbit retinal Müller cells were isolated by means of papaine and mechanical dissociation. These cells were shown to have a well preserved morphology and to preserve viability for many hours. Intense wheat germ agglutinin binding occurs on the photoreceptor side of Müller cells, especially in the microvillous region. Rabbit retinal Müller cells have a Na+,K+-activated adenosine triphosphatase activity in the same order of magnitude as brain astroglial cells.     

Differential Effects of Anionic,Cationic, Nonionic,and Physiologic Surfactants on the Dissociation, α-Chymotryptic Degradation,and Enteral Absorption of Insulin Hexamers

Various surfactants were investigated to compare their effects on insulin dissociation, -chymotryptic degradation, and rat enteral absorption. With a circular dichroism technique, sodium dodecyl sulfate (SDS) at a 5 mM concentration was found to completely dissociate procine-zinc insulin hexamers (0.5 mg/ml) into monomers. The catalytic activity of -chymotrypsin (0.5 µM) was also abolished by 5 mM SDS. When insulin was injected into the distal jejunum/ proximal ileum segment of the rat, 5 mM SDS greatly enhanced its pharmacological availability, from a negligible value to 2.8%. Being a cationic surfactant, hexadecyl trimethylammonium bromide (CTAB) also efficiently dissociated insulin hexamers at concentrations of 1–5 mM. However, extensive charge–charge interaction was observed below a CTAB concentration of 0.6 mM, leading to insulin precipitation at a molar CTAB:insulin ratio of 1:1 to 2:1. An -chymotryptic degradation study also revealed near-complete dissociation of insulin hexamers at 1 mM CTAB. Above 1 mM, however, CTAB acted as an enzyme inhibitor, most likely by means of charge repulsion. Enteral absorption studies showed a much lower pharmacological availability, only 0.29%. Nonionic surfactants such as Tween 80 and polyoxyethylene 9 lauryl ether were ineffective in dissociating insulin hexamers. Tween 80, at 5 mM, neither significantly altered the -chymotryptic degradation pattern nor enhanced the enteral absorption of insulin. The relative effectiveness of different species of bile salts on insulin hexamer dissociation appeared to be similar. Sodium glycocholate at a 30 mM concentration also significantly increased insulin pharmacological availability, to 2.3%. A morphological study did not reveal any significant alteration of the rat intestinal mucosal integrity after exposure to 5 mM SDS for 30 min. The results further emphasize the importance of the degree of insulin aggregation on its enteral transport.     

From hysterical psychosis to Reactive Dissociative Psychosis

In this paper Reactive Dissociative Psychosis (RDP) is seen as a post-traumatic stress response and as a subcategory of Brief Reactive Psychosis (BRP). A review of the literature and the evolution of RDP from Hysteria and Hysterical Psychosis are given. Issue is taken with defining the duration of BRP as Brief. The authors argue that long-standing psychotic symptoms may be traumatically induced. The dissociative aspects of RDP as its key feature and the concomitant implications for accurate diagnosis are proposed. The usefulness of applying hypnosis in RDP treatment is summarized in a case study from Janet and detailed in a case from the authors' practice.This article was accepted for publication under the Editorship of Charles Charles R. Figley.     

Periodic isorhythmic dissociation during enflurane anesthesia in a patient with Sinus Bradycardia

Key words  dysrhythmia - isorhythmic dissociation - oscillation     

Dissociation, Posttraumatic Symptomatology, and Sexual Revictimization: A Prospective Examination of Mediator and Moderator Effects

Using prospective data gathered from a sample of 323 college women over a 10-week academic quarter, the present study examined whether dissociation and posttraumatic symptomatology mediate or moderate sexual revictimization. Results indicated that posttraumatic symptomatology, but not dissociation, moderated the link between previous and subsequent sexual victimization. Neither posttraumatic symptomatology nor dissociation mediated revictimization.     

Properties of hemoglobin and dextran-hemoglobin rightshifted by oxidized inositol tetrakisphosphate

Phytate was digested by wheat bran phytase to yield inositol tetrakisphosphate. Periodate-oxidized inositol tetrakisphosphate (oxyIP4) was coupled by means of reductive alkylation to hemoglobin and the covalent dextran-hemoglobin conjugate to yield the rightshifted (rs) compounds rsHb and rsDxHb, respectively. The variations of the oxygen dissociation curves of these molecules with pH and temperature were compared to those of hemoglobin. The variations with pH were found to be less pronounced for these rightshifted forms. An extensive decrease in the half-saturation oxygen tension was observed, however, with both rsHb and rsDxHb, as in the case of unmodified Hb. Modification of hemoglobin by oxyIP4 at the polyphosphate site was suggested by the lack of a further rightshifting effect of phytate on rsHb, and by the similarity between the difference spectrum of rs-methemoglobin and the difference spectrum induced by the addition of phytate.     

Spatial and Temporal Patterns of Neurogenesis in the Chick Retina

Chick embryo retinas were labelled in ovo by single injections of [3H]thymidine at selected times between days 2 and 12 of incubation. Embryos were later removed, at different stages of development, and the retinas processed for autoradiography of either serial sections or dissociated cell preparations. Analysis of unlabelled cells shows that neurogenesis starts, on day 2 of incubation, in a dorsotemporal area of the central retina, close to the posterior pole and to the optic nerve head. A gradient of neurogenesis spreads from this central area to the periphery, where neurogenesis ends, shortly after day 12, when the last few bipolar cells withdraw from the cell cycle. Additional dorsal-to-ventral and temporal-to-nasal gradients can be discerned in our autoradiographs. In all retinal sectors, ganglion cells start first to withdraw from the cell cycle, followed, with substantial overlapping, by amacrine, horizontal, photoreceptor plus Müller, and bipolar neuroblasts. Ganglion cells are also the first to reach the 50% level of unlabelled cells, followed this time by horizontal, photoreceptor, amacrine, Müller and bipolar cells. Finally, 100% levels of unlabelled cell populations are attained simultaneously by ganglion, horizontal and photoreceptor cells, followed by amacrine, then by Müller, and last by bipolar cells. Although all classes of neurons, in varying proportions, are being produced most of the time, our results also demonstrate that, in any given retinal area, the first cells leaving the cycle are determined to become ganglion cells, and the last ones bipolar cells, and not other types.     

Ataque de Nervios and History of Childhood Trauma

Objective: Ataque de nervios is a common, self-labeled Hispanic folk diagnosis. It typically describes episodic, dramatic outbursts of negative emotion in response to a stressor, sometimes involving destructive behavior. Dissociation and affective dysregulation during such episodes suggested a link to childhood trauma. We therefore assessed psychiatric diagnoses, history of ataque, and childhood trauma in treatment-seeking Hispanic outpatients (N = 70). Significantly more subjects with an anxiety or affective disorder plus ataque reported a history of physical abuse, sexual abuse, and/or or a substance-abusing caretaker than those with psychiatric disorder but no ataque. In some Hispanic individuals, ataque may represent a culturally sanctioned expression of extreme affect dysregulation associated with childhood trauma. Patients with ataque de nervios should receive a thorough traumatic history assessment.     

三重再摄取抑制剂从单胺转运体解离的拉伸分子动力学模拟研究

目的 研究三重再摄取抑制剂(triple reuptake inhibitors,TRIs)与人类单胺转运体(human monoamine transporters,hMATs)的解离机制。方法 采用拉伸分子动力学的方法模拟3个TRIs从hSERT、hNET和hDAT主要结合位点解离的动态过程;通过计算解离过程中施加的外力随模拟时间的变化,分析抑制剂解离过程中重要的蛋白-配体间的相互作用;最后通过Jarzynski方程的二次累积展开式计算抑制剂在3种转运蛋白的平均力势。结果 力谱图曲线表明影响TRIs解离的残基在单胺转运蛋白上的分布主要如下：跨膜区域(TM1b、TM3、TM6a、TM10)和胞外Loop区域(EL2、EL4、EL5、EL6),其中主要结合口袋附近的残基极大地阻碍TRIs的解离。比较每个体系的平均力势数值,结果表明EB1020相比NS2359和SEP225289更容易从蛋白中解离。结论 本研究从原子水平揭示了hMATs与TRIs结合-解离机制,为基于结构的选择性抗抑郁药物设计提供了理论依据。