To test the hypothesis that vitamin C protects against cognitive impairment, the authors conducted a cohort study (n=117) in a retirement community in Sydney, Australia. Vitamin C intake was assessed at baseline (1991) with a semiquantitative food frequency questionnaire, and cognitive function was assessed 4 years later (1995). After adjustment for age, sex, smoking, education, total energy intake, and use of psychotropic medications, consumption of vitamin C supplements was associated with a lower prevalence of more severe cognitive impairment (based on scores on the Mini-Mental State Examination; adjusted odds ratio=0.39, 95% confidence interval 0.18-0.84). There were no associations between vitamin C intake and scores on tests of verbal and category fluency. This study suggests that vitamin C might protect against cognitive impairment.

The TEG V R 5000 and novel TEG V R 6s measure the viscoelasticity of whole blood during in vitro clot formation. The two devices measure similar coagulation variables but utilize distinctly different technologies. This study aimed to determine the correlation and agreement between the thrombelastographic parameters obtained by the two devices during liver transplant surgery. We obtained blood samples at six predefined intervals during the surgery of 10 consecutive patients. Two operators proficient in the use of the TEG V R 6s and TEG V R 5000 systems performed thrombelastographic measurements on each sample: non-citrated TEG V R 5000, citrated TEG V R 5000 and citrated TEG V R 6s. Agreement and correlation were assessed using Bland Altman plots and Lin's concordance correlation. There was considerable inter-device variability for the different parameters measured by the TEG V R 5000 and TEG V R 6s devices. Acceptable agreement was observed when results were within the normal reference ranges. However, with increasing coagulopathy, agreement was poor and results could not be considered interchangeable. Although each of the three tests appeared reliable for qualitative detection of abnormalities of clot formation during liver transplant surgery, we found their quantitative results were not interchangeable.

Hyperventilation (HV) and respiratory alkalosis are associated with hypophosphataemia, although the extent and duration of HV required to produce changes in serum phosphate levels are not known. We sought to characterize the effects of HV, with or without dextrose loading, on serum phosphate levels and other biochemical parameters. HV was monitored by controlling the end-tidal partial pressure of carbon dioxide (PETCO(2)). The effect of dextrose was studied because infusion of a glucose load is known to promote a fall in serum phosphate via stimulation of glycolysis. Eight healthy volunteers were enrolled in four study protocols: (1) HV for 20 min to a PETCO(2) of 25-30 mmHg (mild); (2) HV for 20 min to a PETCO(2) of 15-20 mmHg (severe); (3) mild HV with intravenous dextrose loading, and (4) dextrose loading alone. Periodic measurements of serum phosphate, venous pH, serum 2,3-diphosphoglycerate (2,3-DPG) and other parameters were made. Serum phosphate fell during HV and continued to decline after cessation of HV. Dextrose loading alone caused a fall in serum phosphate that continued for at least 30 min after cessation of the infusion (P<0.0002). HV combined with dextrose resulted in a greater decline in serum phosphate than either variable alone (P=0.003). The maximal decline in serum phosphate occurred in severe HV, with a mean decrease of 0.38 mmol/l at 20 min after cessation of HV (P<0.0001). Serum phosphate was still significantly lowered compared with baseline at 90 min after cessation of HV (P=0.001). Other significant changes seen with HV included a decrease in serum glucose (P<0.01), a decrease in serum potassium (P<0.05) and an increase in venous pH (P<0.007). Serum 2, 3-DPG levels did not change significantly in any study protocol. Thus relatively mild acute HV produces significant changes in serum phosphate. In both mild and severe HV this effect is progressive after cessation of HV. This phenomenon has not been shown before, and may have significant clinical implications.