Maximal and submaximal oxygen uptake during running: how should body mass be accounted for?

Oxygen uptake during running, i.e., the running economy, is an important factor in determining running performance in endurance events. The relation to performance is particularly strong when the aerobic running capacity is calculated, i.e., when running economy is related to the maximal oxygen uptake. There is considerable interindividual variation in running economy, and the reason for this is only partly understood. To some extent, this may be due to the way in which the oxygen uptake during running is usually expressed. This may expecially be true when subjects with different or changing body masses are compared. Several lines of evidence, including earlier animal studies as well as more recent human studies, favor the expression of submaximal and maximal oxygen uptake during running in terms of ml · kg^−0.75· min⁻¹ rather than as ml · kg⁻¹· min^−1.     

Autotransfusion after open heart surgery: the oxygen delivery capacity of shed mediastinal blood is maintained

Autotransfusion of mediastinal shed blood after open heart surgery has become a common and accepted procedure in reducing the need for homologous transfusion during the last 15 years. The objectives of the present study were to investigate the oxygen delivery capacity of autotransfused shed mediastinal blood, compared to patient-blood, during cardiopulmonary bypass and in the postoperative period.
Ten consecutive patients undergoing elective cardiac surgery were studied. Mediastinal shed blood was collected in the cardiotomy reservoir and retransfused during the first 18 postoperative hours. The oxygen delivery capacity of the blood to the tissues was calculated by use of the oxygen status algorithm (OSA 2.0) programme and measurement of the 2,3-diphosphoglycerate (2,3-DPG) concentration.
Autotransfusion volume ranged from 450–1530 ml per patient (median 824 ml). Shed blood had a mean haemoglobin level of 8.8 g/dl and 7.4 g/dl at 1 h and 6 h of autotransfusion, respectively. There were no significant changes of 2,3-DPG concentration in the patient-blood during cardiopulmonary bypass or after autotransfusion compared to preoperative values. P50 for oxygen (3.6 and 3.6 kPa) and 2,3-DPG concentrations (5.3 and 5.1 mikromol/ml erythrocyte) in shed mediastinal blood (1h and 6h postoperatively) were not significantly different compared to patient-blood.
The results demonstrate that the oxygen delivery capacity of shed mediastinal blood is maintained and that the oxygen affinity of patient-blood is not influenced by autotransfusion.     

Cavernous sinus involvement in recurrent Nelson's syndrome

Summary Two cases of meningiomas, which are considered to have been caused by the preceding irradiation, are reported. In both cases, the cytokinetic study of the tumour using bromodeoxyuridine (BrdU) was performed. The percent of the tumour cells in the S phase of the cell cycle was less than 1% in both cases. The low labelling indices might suggest a relatively slow growing potential of these tumours, though the radiation-induced meningiomas were reported as being rapidly growing and malignant.     

Fluctuating PEEP (F–PEEP) versus conventional PEEP in dogs with asymmetrical lung injury

Fluctuating PEEP (F-PEEP) is a newly developed PEEP in which end-expiratory pressure (EEP) is periodically changed within a certain range. In a dog model with unilateral lung injury induced by the introduction of hydrochloric acid, F-PEEP in which the EEP was periodically changed from 0.5 to 1.5 kPa at periods of 6 min, and conventional PEEP (C-PEEP) with an optimized EEP of 1.0 kPa, were each applied for 30 min. F-PEEP produced a significantly greater improvement of PaO2 and intrapulmonary shunt (QS/QT) than C-PEEP, and at the low EEP phase, the greatest improvement accompanied by an increased dynamic compliance and a large cardiac output was obtained. These results suggest that F-PEEP provides a useful mode of artificial ventilation for the treatment of unilateral lung injury.     

Effects of monoamine uptake inhibitors given early postnatally on monoamines in the brain stem,caudate/putamen and cortex,and on dopamine D1 and D2 receptors in the caudate/putamen

Summary Rats were treated with desipramine 5mg/kg, nomifensine 10mg/kg, zimelidine 25 mg/kg or with 0.9% sodium chloride once a day during the second and third weeks after birth, and brain stem, caudate/putamen and cortical monoamines, and caudate/putamen dopamine D₁ (³[H]SCH 23390) and D₂ (³[H]spiroperidol) receptor binding were measured when rats were at two months of age. In the brain stem, the concentration of 3-methoxy-4-hydroxy-phenyl glycol was increased in nomifensine rats and the ratio of 5-hydroxyindoleacetic acid to 5-hydroxytryptamine was increased in zimelidine rats. In the caudate/putamen, the concentrations of 3,4-dihydroxyphenylacetic acid and homovanillic acid and the ratio of homovanillic acid to dopamine were increased in desipramine rats; neither³[H]SCH 23390 nor³[H]spiroperidol binding were affected by any of the three monoamine uptake inhibiting antidepressants studied. In the cortex, the ratio of 5-hydroxyindoleacetic acid to 5-hydroxytryptamine was increased in desipramine and zimelidine rats. The findings suggest that desipramine but not nomifensine increases the metabolism of dopamine in the caudate/ putamen and nomifensine but not desipramine increases the metabolism of norepinephrine in the brain stem, and furthermore that the metabolism of serotonin is affected by desipramine as well as by zimelidine. It is possible that also treatment of women with these drugs during late pregnancy causes long-lasting changes in the brain of human fetus.     

长期居住海平面后藏族经受急性减压低氧时的体力活动能力

本研究从急性低氧对移居海平面后藏族的体力活动能力的影响来探索藏族的高原低氧适应机制。结果揭示藏族的最大体力负荷强度没有显著下降，最大氧耗和氧脉搏也没有明显变化，动脉血氧饱和度明显高于汉族，这更显示藏族对高原低氧适应机制有独特之处。推测可能是藏族在氧的摄取、传递和释放过程比汉族更有利于对高原低氧环境的适应。     

Biochemical evidence for the involvement of central serotonergic neurotransmission in the action of the antidepressant drug Medifoxamine

Medifoxamine, an antidepressant agent which has an original chemical structure, has been shown through in vitro studies, utilising radioligand binding in tissue homogenates, to bind with moderately high affinity to 5-HT_1c and 5-HT₂ receptor subtypes and to 5-HT uptake sites (IC₅₀ 950, 980, and 1,500 nM, respectively). It has been shown to bind in vivo to rat brain 5-HT₂ receptors after acute treatment with high dose (50 mg/kg, i.e., 133.9 μmol/kg). After 14 days continuous treatment with low dose (20 mg/kg, 53.6 μmol/kg), a decrease in the capacity of [³H]-5-HT uptake and a dose-dependent down-regulation of 5-HT₂ receptors in rat cerebral cortex were observed. These results indicate that medifoxamine, which has been shown previously to act through dopaminergic systems, interacts also with central serotonergic neurotransmission and particularly with the 5-HT₂ receptors, which could contribute to its antidepressant effect.     

Benzodiazepine concentrations in brain directly reflect receptor occupancy: studies of diazepam,lorazepam, and oxazepam

Groups of male CF-1 mice received 3 and 10 µmol/kg diazepam, lorazepam, and oxazepam intravenously. Between 1 min and 24 h after injection, benzodiazepine concentrations were determined by gas chromatography (GLC) in plasma and in one brain hemisphere; in the other hemisphere, ex vivo benzodiazepine receptor occupancy was measured using³H-flunitrazepam displacement. Based on GLC data, diazepam entered brain rapidly, and was also cleared rapidly, yielding desmethyldiazepam and oxazepam as metabolites in plasma and brain. However, lorazepam and oxazepam entered brain slowly, with brain:plasma equilibrium achieved at 30–60 min; thereafter, the drugs were eliminated from plasma and brain in parallel. The time course and extent of ex vivo occupancy were highly consistent with GLC data (for diazepam, GLC levels were expressed as the sum of diazepam, desmethyldiazepam, and oxazepam, with metabolite concentrations, normalized for molecular weight and for in vitro benzodiazepine receptor affinity.) Between-method correlations were 0.95 or higher. Thus benzodiazepine receptor occupancy is highly dependent on benzodiazepine concentrations in brain. Differences in the time-course of onset and duration of pharmacologic activity between the highly lipophilic benzodiazepine diazepam and the less lipophilic hydroxylated derivatives lorazepam and oxazepam are largely explained by differences in systemic kinetics and in the rate of uptake into brain.Supported in part by grants MH-34223, DA-05258, and AG-00106 from the United States Public Health Service     

ONCOCYTES OF THE THYROID: A NEUTRAL RED DYE UPTAKE STUDY

Oncocytosis and oncocytomas have attracted attention because on the one hand there have been reports of the favourable prognosis and generally benign nature of oncocytic tumours, while on the other hand, Hurthle cell change in thyroid neoplasms have been reported to be correlated with aggressive biological behaviour and a significantly worse clinical course. Presently, there appear to be two schools of thought on the significance of oncocytosis: (i) a process where there is redifferentiation of cells with involvement in the pathogenesis of cancer; and (ii) a compensatory process for ‘functional exhaustion’ of the cell. Many aspects of oncocytosis seem unclear. In this study, transmission electron microscopy is used to demonstrate the presence of thyroid oncocytes in the hemithyroidectomy specimen of a patient with focal lymphocytic thyroiditis. Tissue sections from this specimen did not display preferential uptake of neutral red dye, a distinctive characteristic of M-phase cancer cells which was previously reported. The findings seem to suggest that oncocytes are not cells with distinctive proliferative potentials. If that were the case, then oncogenesis or cancer cell progression and oncocytosis may not be convergent processes.     

海拔3417m世居及移居者无氧代谢阈与左心功能关系的探讨

在海拔３４１７ｍ对１８名健康世居藏族和１６名移居汉族用Ｊｅａｇｅｒ气体代谢自动分析系统和心阴抗图测定了无氧阈和最大摄氧量时的ＳＶ、ＣＯ、ＰＥＰ／ＬＶＥＴ和ＳａＯ２。结果显示：在海拔３４１７ｍ测得ＡＴ值明显低于海平面；世居藏族ＡＴ出现较晚，并且ＡＴ时的功率、ＶＯ２、ＭＶ、ＨＲ、ＣＯ、ＳＶ均高于移居汉族，而ＰＥＴ／ＬＶＥＴ比值小于移居组；两组的ＳＶ峰值出现时间不同，蕊居组在ＡＴ或ＡＴ以后出现的占７２％