Methaemoglobin formation in the koala and the possum

Measurements were made of glutathione (GSH) levels, catalase activity and the oxidant sensitivity of the erythrocytes from the koala (Phascolarctos cinereus) and the common brushtail possum (Trichosurus vulpecula). The oxidant sensitivity was tested by treating the haemolysates with either 0.55 him H₂O₂ or 1.4mm NaNO₂. The erythrocytes of the koala had greater levels of GSH and catalase and yet were found to be more susceptible to oxidation induced by both these oxidants.     

Uptake of dehydroascorbic acid in high-GSH and normal-GSH dog erythrocytes

Uptake of dehydroascorbic acid (DHA) was studied in two types of dog erythrocytes with high GSH and normal GSH levels. Compared with ascorbic acid uptake, DHA produced a much greater ascorbic acid accumulation in dog erythrocytes. Both dog erythrocytes showed a concentration dependence of DHA uptake, and cellular ascorbic acid concentrations were significantly higher in high-GSH cells than in normal-GSH cells. Glucose and cytochalasin B inhibited DHA uptake. This suggests that DHA enters dog erythrocytes predominantly by the facilitated glucose transporter, particularly by the Glut 1 glucose transporter. The rate of glucose uptake was quite similar in the two types of cells. Compared with normal-GSH cells, high-GSH cells were more resistant to oxidative stress induced by high concentration of DHA. As a rapid entry of DHA inflicts on cells a heavy demand for GSH for its reduction to ascorbic acid, high-GSH cells containing a larger reserve of GSH have an advantage over normal-GSH cells in both ascorbic acid accumulation and resisting oxidative stress produced by DHA.     

Shoulder instability: impact of glenohumeral arthrotomography on treatment

We used arthrotomography to study the glenoid labrum in 114 patients. Sixty-nine of the patients had anatomic instability of the shoulder (including recurrent dislocation and subluxation of the shoulder), and 45 patients had functional instability of the shoulder (denoted by chronic pain, clicking of the joint, and the sensation that an unstable condition exists without the objective signs of it). Labral tears were revealed arthrotomographically in 86% of the patients with anatomic instability, while only 40% of the patients with functional instability had labral abnormalities, and these were primarily of minor severity. Fifty-six patients (44 of whom had anatomic instability; 12, functional instability) required surgery. The surgical findings were correlated with the arthrotomographic findings, and no false-positive results were revealed. However, arthrotomography demonstrated only part of the pathologic condition of two patients. These results confirm that there is a strong correlation between labral pathologic conditions and anatomic instability of the shoulder. Arthrotomographic studies have a great impact on the selection of therapy in cases of both anatomic and functional instability of the shoulder.     

Effects of Hypothermia on Blood Endogenous Endotoxin Levels During Cardiopulmonary Bypass

A bstract Endotoxin activates white blood cells and complement and produces a spectrum of clinical syndromes ranging from fever to septic shock. Although production of endogenous endotoxemia during cardiopulmonary bypass (CPB) has recently been reported, the role of hypothermia on endotoxemia is not clear. In this study, we evaluated the effects of moderate (24–28°C) and mild (32–34°C) hypothermia on blood endotoxin levels. The study population consisted of 20 patients who underwent coronary artery bypass grafting (CABG) with CPB. Moderate systemic hypothermia was applied during aortic cross-clamping in ten patients (group 1) and mild hypothermia in the remaining ten patients (group 2). The mean rectal temperatures were 26.8 ± 1.2°C in group 1 and 33.8 ± 0.8°C in group 2. The blood samples for endotoxin level measurements were obtained before CPB, during aortic cross-clamping, immediately after the release of the cross-clamp, 20 minutes after the release of the cross-clamp, after CPB, and 2 hours postoperatively. There were no endotoxins in any of the samples before CPB, but it was detected after CPB in both groups. The endotoxin levels were significantly higher in group 1 than in group 2. The present study suggests that when hypothermia is the technique of choice, the deleterious effects of endotoxemia on patients with comorbidity must be considered.